Sensing glucose concentrations at GHz frequencies with a fully embedded Biomicro-electromechanical system (BioMEMS).

The progressive scaling in semiconductor technology allows for advanced miniaturization of intelligent systems like implantable biosensors for low-molecular weight analytes. A most relevant application would be the monitoring of glucose in diabetic patients, since no commercial solution is available yet for the continuous and drift-free monitoring of blood sugar levels. We report on a biosensor chip that operates via the binding competition of glucose and dextran to concanavalin A. The sensor is prepared as a fully embedded micro-electromechanical system and operates at GHz frequencies. Glucose concentrations derive from the assay viscosity as determined by the deflection of a 50 nm TiN actuator beam excited by quasi-electrostatic attraction. The GHz detection scheme does not rely on the resonant oscillation of the actuator and safely operates in fluidic environments. This property favorably combines with additional characteristics-(i) measurement times of less than a second, (ii) usage of biocompatible TiN for bio-milieu exposed parts, and (iii) small volume of less than 1 mm3-to qualify the sensor chip as key component in a continuous glucose monitor for the interstitial tissue.

X-ray photoelectron and scanning Auger electron spectroscopy study of electrodeposited ZnCr coatings on steel.

Zn-Cr alloyed coatings electrochemically deposited are of high interest for leading steel manufacturing companies because of their novel properties and high corrosion resistance compared with conventional Zn coatings on steel. For tuning and optimizing the properties of the electrodeposited Zn-Cr coatings, a broad range of the deposition conditions must be studied. For this reason, two different types of material were investigated in this study, one with a low electrolyte temperature and one with an elevated electrolyte pH, compared with the standard values. Because different corrosion performance and delamination behaviour of the layers were observed for the two types, advanced surface analysis was conducted to understand the origin of this behaviour and to discover differences in the formation of the coatings. The topmost surface, the shallow subsurface region, and the whole bulk down to the coating-steel interface surface were analysed in detail by X-ray photoelectron spectroscopy (XPS) and high-resolution scanning Auger electron spectroscopy to determine the elemental and the chemical composition. For better understanding of the resulting layer structure, multiple reference samples and materials were measured and their Auger and XPS spectra were fitted to the experimental data. The results showed that one coating type is composed of metallic Zn and Cr, with oxide residing only on the surface and interface, whereas the other type contains significant amounts of Zn and Cr oxides throughout the whole coating thickness.

Genetic control by cis-acting regulatory RNAs in Bacillus subtilis: general principles and prospects for discovery.

In recent years, Bacillus subtilis, the model organism for gram-positive bacteria, has been a focal point for study of posttranscriptional regulation. In this bacterium, more than 70 regulatory RNAs have been discovered that respond to intracellular proteins, tRNAs, and small-molecule metabolites. In total, these RNA elements are responsible for genetic control of more than 4.1% of the genome-coding capacity. This pool of RNA-based regulatory elements is now large enough that it has become a worthwhile endeavor to examine their general features and to extrapolate these simple observations to the remaining genome in an effort to predict how many more may remain unidentified. Furthermore, both metabolite- and tRNA-sensing regulatory RNAs are remarkably widespread throughout eubacteria, and it is therefore becoming increasingly clear that some of the observations for B. subtilis gene regulation will be generally applicable to many different species.

The GA motif: an RNA element common to bacterial antitermination systems, rRNA, and eukaryotic RNAs.

Two different transcription termination control mechanisms, the T box and S box systems, are used to regulate transcription of many bacterial aminoacyl-tRNA synthetase, amino acid biosynthesis, and amino acid transport genes. Both of these regulatory mechanisms involve an untranslated mRNA leader region capable of adopting alternate structural conformations that result in transcription termination or transcription elongation into the downstream region. Comparative analyses revealed a small RNA secondary structural element, designated the GA motif, that is highly conserved in both T box and S box leader sequences. The motif consists of two short helices separated by an asymmetric internal loop, with highly conserved GA dinucleotide sequences on either side of the internal loop. Site-directed mutagenesis of this motif in model T and S box leader sequences indicated that it is essential for transcriptional regulation in both systems. This motif is similar to the binding site of yeast ribosomal protein L30, the Snu13p binding sites found in U4 snRNA and box C/D snoRNAs, and two elements in 23S rRNA.

Completing the continuum of care. The growth of a pediatric hospice program.

This article examines the process of integrating a pediatric program into an existing hospice organization. It also discusses the five phases a child and family experience, from entering hospice through grieving the loss of the child.

[Application of the chromatographic-spectrophotometric method for the analytical control of l-ascorbic acid in pharmaceutical and plant material]. / Zastosowanie metody chromatograficzno-spektrofotometrycznej do analitycznej kontroli kwasu L-askorbinowego w materiale farmaceutycznym i roslinnym.

The conditions of chromatographic separation allowing the isolation of L-ascorbic acid from its products of decomposition and other accompanying substances in the determined pharmaceutic preparation and plant materials were established. The isolated L-ascorbic acid was signed by the extractive--spectrophotometric method using coupled redox-complexation reactions with iron(III), 1, 10 phenantroline and bromophenol blue system. The analytical procedure allowing the evaluation of durability of vitamin C in multivitamin "Vitaral" preparate was described. The procedure was used also for the evaluation of the loss of L-ascorbic acid in the parsley and lovage in the process of drying and storage.

The use of phenylfluorone in the presence of cetylpyridinium chloride and Triton X-100 for the spectrophotometric determination of copper(II) in blood serum.

A simple and sensitive spectrophotometric method for determination of copper(II) is based on the formation of a blue coloured complex of Cu(II) with 9-phenyl-2,3,7-trihydroxy-6-fluorone (PF) in the presence of cetylpyridinium chloride (CP) and Triton X-100, has been developed. Optimum concentrations of PF, CP, Triton X-100 and pH ensuring maximum absorbance were defined. The complex Cu(II)-PF-CP-Triton X-100 shows maximum absorbance at 595 nm with a molar absorptivity value of 9.67x10(4) l mol(-1) cm(-1). The detection limit of the method is 0.028 mug ml(-1). Beer's law is obeyed for copper concentrations in the range 0.04-0.4 mug ml(-1). The studies of the effect of foreign ions on determination of copper, show that the selectivity of the method is poor. The cations of alkali metals and anions Br(-), Cl(-), I(-), F(-), NO(2)(-), NO(3)(-), CH(3)COO(-), SO(4)(2-), S(2)O(3)(2-), PO(4)(3-), citrates (examined in 1000-fold molar excess over copper) do not affect the determination. All cations forming complexes with PF have an interfering effect. The statistical evaluation of the method was carried out for six determinations using 10 mug of Cu and the following results were obtained: the standard deviation, SD=0.042, the confidence interval mu(95)=10.1+/-0.1 mug Cu. The method has been applied for determination of copper in blood serum.

[Vena cava filter for prevention of pulmonary embolism]. / Cavafilter zur Prophylaxe von Pulmonalembolien.

Vena caval filters in the prevention of pulmonary embolism All currently available caval filters can be implanted percutaneously in local anaesthesia. In the USA the FDA has approved the stainless steel Greenfield filter, the Titanium Greenfield filter, the Bird's Nest filter, the LGM or VenaTech filter and the Simon Nitinol filter. Some other caval filters are commercially available in Europe, but there exist only few clinical trials about them. The Greenfield filter is implanted since the early seventies and the greatest amount of data has been published about it. Standard indications for filter placement are recurrent pulmonary embolism despite adequate anticoagulation, in patients after pulmonary embolectomy, when there is a contraindication to anticoagulation (e.g. fresh surgical wound, active gastrointestinal bleeding, recent haemorrhagic stroke, major trauma,...) and when serious complications occur after thrombolysis or anticoagulation. In patients who suffer from severe cardiopulmonary disease both a caval filter and anticoagulation may be required. Follow-up investigations include plain abdominal radiography and duplex ultrasound, in special cases computed tomography, cavography, magnetic resonance imaging in newer filter types, and intravascular ultrasound. Complications include recurrent pulmonary embolism, caval obstruction, migration, fracture and perforation of filter struts. As clinically relevant complications are rare, in diligently selected cases the patient will benefit from implantation of a caval filter.

Transcranial Doppler for early identification of potential organ transplant donors.

BACKGROUND: Encouraging results in transplant medicine create a growing demand for organ transplant donors. Transcranial Doppler (TCD) has been used by several investigators to assess arrest of the cerebral circulation in brain dead patients. We report on TCD as a monitoring tool for early identification of potential organ transplant donors. DESIGN: A prospective clinical study. SETTING: Intensive care unit (ICU) of a 900-bed community hospital (primary and tertiary care center) in Vienna, Austria. SUBJECTS AND METHODS: All patients with acute intracranial lesions admitted to our intensive care unit underwent TCD examination at least once daily. In patients with Glasgow Coma Scores < 7, TCD waveforms with high resistance profiles unchanged by therapeutic attempts to lower intracranial pressure indicated the need for repeated TCD up to four times a day. TCD waveform abnormality consisting of absent or reversed diastolic flow or small early systolic spikes in at least two intracranial arteries was considered to constitute intracranial circulatory arrest. Brain death was confirmed by clinical criteria, an isoelectric electroencephalography (EEG) or non filling of the intracerebral arteries on arteriography. RESULTS: From January 1994 to July 1996 we identified 11 comatose patients as potential organ transplant donors with typical TCD findings indicating intracranial circulatory arrest. Diagnosis was subarachnoid hemorrhage in 7 and intracerebral hemorrhage in 4 patients. Brain death diagnosis according to the criteria of Austrian law was initiated immediately after the TCD findings suggested intracranial circulatory arrest. Confirmation of brain death was obtained by clinical criteria and either EEG (6 patients) or cerebral angiography (5 patients). CONCLUSION: TCD examinations on a daily routine basis offer a noninvasive monitoring method for early assessment of intracranial circulatory arrest. TCD enables quick identification and further diagnosis of candidates for organ transplant donation.

Glu-tRNAGln amidotransferase: a novel heterotrimeric enzyme required for correct decoding of glutamine codons during translation.

The three genes, gatC, gatA, and gatB, which constitute the transcriptional unit of the Bacillus subtilis glutamyl-tRNAGln amidotransferase have been cloned. Expression of this transcriptional unit results in the production of a heterotrimeric protein that has been purified to homogeneity. The enzyme furnishes a means for formation of correctly charged Gln-tRNAGln through the transamidation of misacylated Glu-tRNAGln, functionally replacing the lack of glutaminyl-tRNA synthetase activity in Gram-positive eubacteria, cyanobacteria, Archaea, and organelles. Disruption of this operon is lethal. This demonstrates that transamidation is the only pathway to Gln-tRNAGln in B. subtilis and that glutamyl-tRNAGln amidotransferase is a novel and essential component of the translational apparatus.

Nonsteric factors dominate binding of nitric oxide, azide, imidazole, cyanide, and fluoride to the rhizobial heme-based oxygen sensor FixL.

BACKGROUND: The FixL protein is a heme-based sensor. Binding of oxygen to a unique heme domain inhibits a kinase domain of the type found in two-component regulators. Oxygen association is slow, but the dissociation rate is comparable to that of myoglobins. We have probed the size and chemistry of the FixL heme pocket by measuring the affinites, on rates and off rates for a wide variety of ferric heme ligands. Cyanide, but not fluoride, regulates the kinase activity. To examine how the sensory heme domain interacts with the kinase, we asked how the presence of the kinase domain affects ligand binding. RESULTS: The affinities of ferric FixL for heme ligands follow the same trend as their pKa values: cyanide > 4-methyl imidazole > imidazole > fluoride > azide >> thiocyanate. The association rates follow the reverse trend. Striking differences from myoglobin include a 6-fold greater affinity for, and faster binding to, the bulky ligand imidazole, a 14-fold faster on rate for nitric oxide, a 2 800-fold lower affinity for azide, and a complete failure to bind thiocyanate. The presence of the kinase domain does not alter the affinity or binding kinetics of the high-spin ligand fluoride, but affects the off rates of other ligands. The EPR spectrum shows a characteristic pentacoordinate nitrosyl heme, indicating that the Fe-His bond in FixL is strained. CONCLUSIONS: The importance of ligand deprotonation to the on rates and the fact that large ligands bind readily indicate that the heme pocket is open and apolar. Ligand basicity strongly influences the strength of binding. The destabilization of inhibitory ligands by the presence of the kinase domain is consistent with a 'load' imposed by coupling to the inactivating mechanism.

Sex-related differences in acetazolamide-induced cerebral vasomotor reactivity.

BACKGROUND AND PURPOSE: Cerebral vasomotor reactivity can easily be assessed reliably by measuring vasodilatory response to acetazolamide by transcranial Doppler sonography. The aim of this study was to confirm the hypothesis that female sex is associated with an increased cerebrovascular flow reserve. METHODS: Blood flow velocity of the middle cerebral artery was measured by transcranial Doppler sonography in 36 healthy sex- and age-matched subjects. After the initial blood flow velocities were recorded, the subjects received 14.3 mg/kg body wt acetazolamide, ie, 1 g/70 kg, intravenously. The measurements were repeatedly performed at 5-minute intervals starting 10 minutes after injection and lasting for 30 minutes. The highest measured flow velocities were used for further analysis. RESULTS: In both groups mean blood flow velocity increased significantly after acetazolamide (women, from 60.2 +/- 12.5 to 89.9 +/- 14.4 cm/s, P < .006; men, from 54.5 +/- 18.8 to 75.7 +/- 24.5 cm/s, P < .02). The difference in mean blood flow velocity after acetazolamide between groups of women and men was statistically significant (P < .02). CONCLUSIONS: Female subjects show an increased vasodilatory response to the acetazolamide test compared with men.

A versatile electronic drive for rehabilitation devices, vehicles for the disabled and senior citizens.

Electronic drives have various applications in rehabilitation devices, partly to strengthen muscles of specific parts of the body (e.g. legs), partly to support the mobility of the patient during the rehabilitation process. Physically disabled people with limited walking ability also benefit from support devices equipped with electrical drives, and senior citizens often appreciate easy-to-handle, quiet and cost-effective individual transport means for local traffic. The paper describes a versatile, novel electronic drive, consisting of an electric motor and a control circuit. Explanations concentrate on the design goals and solutions that guarantee a smooth transition between muscle- and electric driving of the different devices or vehicles, and the benefits of the very high efficiency of the drive, like reduced weight or extended range.

[Determining the duration of suspended license for alcohol intoxicated drivers]. / Die Bemessung der Sperrfrist bei alkoholauffälligen Kraftfahrern.

Public safety on the road and the need of each individual to participate in road traffic call for drink drivers to be dealt with legally. They should be dealt with in a preventive, successful and individual manner. The insuperable difficulties encountered by a criminal judge when having to determine the type, extent and duration of the offence as well as determining the motivation for improvement, would justify the judge not having to determine the period of suspension as well. This could be achieved by introducing a minimum period of suspension for all offenders. For those interested in reacquiring their driving licence, directives should be imposed so that appropriate and individual steps can be taken right at the beginning of their suspension, in order that their suitability for road traffic can be restored. In that case Sunder's question asked at the beginning could be answered as follows: "The authority to withdraw driving licences should not be withdrawn from the judge."

Glutamine dipeptide-supplemented parenteral nutrition reverses gut atrophy, disaccharidase enzyme activity, and absorption in rats.

BACKGROUND: Total parenteral nutrition (TPN) is associated with intestinal atrophy and dysfunction possibly attributed to the absence of the nonessential amino acid glutamine from commercially available TPN solutions because of the instability of the monoamino acid during heat sterilization and storage. The use of stable dipeptides may overcome this problem. In this study we tested the hypothesis that glutamine dipeptide supplementation with alanyl-L-glutamine during TPN for 10 days would reverse small bowel atrophy and TPN-induced dysfunction in rats. METHODS: A conventional TPN solution (250 kcal/kg bw) was compared with an isocaloric and isonitrogenous TPN supplemented with alanyl-L-glutamine dipeptide. A food-fed control group was included (n = 6 each group). Jejunum mucosal architecture, absorption of water and glucose, and disaccharidase activity of maltase and alkaline phosphatase were evaluated. RESULTS: TPN-induced villous atrophy, significantly reduced absorption rate, and decreased activity of villous enzymes, compared with the TPN group, could be reversed by supplementation of glutamine dipeptide alanyl-L-glutamine to parenteral nutrition solutions with no difference to the control group. CONCLUSIONS: Glutamine dipeptide-enriched parenteral nutrition preserves mucosal structure and reversed atrophy-associated dysfunction.

False diagnosis of myocardial infarction due to an extreme left sided cardiac rotation in two patients.

We present two patients with an extremely rare condition: abnormal cardiac levoposition. Alterations in the ECG caused by this congenital abnormality and additional chest symptoms led to the false diagnosis of previous myocardial infarction. Chest X-ray and echocardiography suggested cardiac malformation. Correct diagnosis of cardiac levoposition was established by magnetic resonance imaging.

Management of common bile duct stones in the era of laparoscopic cholecystectomy.

PURPOSE: To assess the safety and efficacy of endoscopic retrograde cholangiopancreatography (ERCP) prior to laparoscopic cholecystectomy. METHODS: In patients suspected of harboring common duct stones, we performed ERCP prior to laparoscopic cholecystectomy (LC). Indications included jaundice, gallstone pancreatitis, elevated liver function tests, and visualizing a common duct stone and/or a dilated common duct on ultrasonography. Data were analyzed retrospectively. RESULTS: Of 217 patients undergoing LC, 37 (17%) had ERCP with or without endoscopic sphincterotomy (ES). Of these 37, common duct stones were noted in 19 patients (51%). Only 1 of 11 (9%) patients with mild gallstone pancreatitis had choledocholithiasis. The only complication following ERCP was pancreatitis in 1 patient who underwent uneventful LC. There were no deaths in the entire series. CONCLUSIONS: ERCP and ES is a safe and effective method of clearing the common duct of stones prior to LC. Patients with mild gallstone pancreatitis do not require ERCP prior to LC.