Selectively arranged single-wire based nanosensor array systems for gas monitoring.

Gas nanosensors, comprised of arrays of nanoelectrodes with finger-widths of ∼100 nm developed by electron beam lithography and aerosol assisted chemical vapor deposited non-functionalized and Pt-functionalized tungsten oxide nanowires (<100 nm) subsequently integrated across the pairs of electrodes via the dielectrophoresis method, are developed in this work. The functionality of these devices is validated towards various concentrations of NO2 and C2H5OH. The results demonstrate reproducible and consistent responses with better sensitivity and partial selectivity for the non-functionalized systems to NO2, as opposed to the Pt-functionalized systems, which display better sensing properties towards C2H5OH with a loss of response to NO2. These results are explained on the basis of the additional chemical and electronic interactions at the Pt/tungsten oxide interface, which increase the pre-adsorption of oxygen species and make the functionalized surface rather more sensitive to C2H5OH than to NO2, in contrast to the non-functionalized surface.

Neurochemical effects of L-pyroglutamic acid.

The effect of L-pyroglutamic acid, a metabolite that accumulates in pyroglutamic aciduria, on different neurochemical parameters was investigated in adult male Wistar rats. Glutamate binding, adenylate cyclase activity and G protein coupling to adenylate cyclase were assayed in the presence of the acid. L-pyroglutamic acid decreased Na(+)-dependent and Na(+)-independent glutamate binding. Basal and GMP-PNP stimulated adenylate cyclase activity were not affected by the acid. Furthermore, rats received unilateral intrastriatal injections of 10-300 nmol of buffered L-pyroglutamic acid. Vehicle (0.25 M Tris-Cl, pH 7.35-7.4) was injected into the contralateral striatum. Neurotoxic damage was assessed seven days after the injection by histological examination and by weighing both cerebral hemispheres. No difference in histology or weight could be identified between hemispheres. These results suggest that, although capable of interfering with glutamate binding, pyroglutamate did not cause a major lesion in the present model of neurotoxicity.

Effects of postnatal methylmalonate administration on neurobehavioral development of rats.

Administration of methylmalonic acid in rats has been used as a model for methylmalonicacidemia in humans. Nestling Wistar rats of both sexes received 5 injections daily at 3-h intervals (starting at 7:30 a.m.) of saline or methylmalonic acid (MMA, 10 mg/ml) in a volume of 9 microliters/g body weight per injection subcutaneously in the lumbar region from the 5th to the 9th day of life and 11 microliters/g from day 10 to 14. Growth and neuromotor development were assessed by monitoring the following parameters daily in 54 rats: body weight, ear unfolding, incisor eruption, eye opening, righting, palmar grasp, negative geotaxis, cliff avoidance, free-fall righting and startle reflex. The only statistically significant effects of MMA administration were on the day of appearance of the free-fall righting reflex: MMA, 12.44 +/- 1.55 vs 11.0 +/- 0.39 days for saline control (P < 0.05, by two-way ANOVA) and a significant decrease in weight (P < 0.05, by ANOVA with repeated measures). The results suggest that chronic MMA administration to rats has a selective effect on neuromotor development.

Effects of postnatal methylmalonate administration on neurobehavioral development of rats

Administration of methylmalonic acid in rats has been used as a model for methylmalonicacidemia in humans. Nestling Wistar rats of both sexes received 5 injections daily at 3-h intervals (starting at 7:30 a.m.) of saline or methylmalonic acid (MMA, 10 mg/ml) in a volume of 9 microliters/g body weight per injection subcutaneously in the lumbar region from the 5th to the 9th day of life and 11 microliters/g from day 10 to 14. Growth and neuromotor development were assessed by monitoring the following parameters daily in 54 rats: body weight, ear unfolding, incisor eruption, eye opening, righting, palmar grasp, negative geotaxis, cliff avoidance, free-fall righting and startle reflex. The only statistically significant effects of MMA administration were on the day of appearance of the free-fall righting reflex: MMA, 12.44 +/- 1.55 vs 11.0 +/- 0.39 days for saline control (P < 0.05, by two-way ANOVA) and a significant decrease in weight (P < 0.05, by ANOVA with repeated measures). The results suggest that chronic MMA administration to rats has a selective effect on neuromotor development

Occupational asthma caused by guar gum.

Some vegetable gums have been reported to cause asthma. We describe three subjects who were exposed at work to guar gum, which is derived from the outer part of Cyanopsis tetragonolobus, a vegetable that grows in India. The first subject worked for a pharmaceutical company; the second and third subjects worked at a carpet-manufacturing plant. All three subjects developed symptoms of rhinitis and asthma after the onset of exposure to guar gum. All subjects were atopic and demonstrated mild bronchial hyperresponsiveness to inhaled histamine at the time they were observed. Skin prick tests demonstrated an immediate skin reaction to guar gum. All three subjects had high levels of serum IgE antibodies to guar gum. Specific inhalation challenges in which the three subjects were exposed for short intervals (less than or equal to 4 minutes) to powder of guar gum elicited isolated immediate bronchospastic reactions in two subjects and a dual reaction in the other subject.

Diagnostic ultrasound equipment. Safety and dosimetry.

A survey of present opinions on the safety of diagnostic ultrasound applications is presented together with some data on output levels. Physical mechanisms involved in potential adverse effects are described. Labelling requirements of the equipment are defined and specified. These requirements are contained in a recent proposal of the Netherlands' Committee on the Safety of Ultrasound.

Chronic ethanol administration depresses fatty acid synthesis in rat adipose tissue.

Administration of ethanol as part of a nutritionally adequate liquid diet to female Wistar rats was found to depress markedly incorporation of labelled glucose into adipose-tissue acylglycerol fatty acids. Similar results with labelled pyruvate and acetate suggested inhibition of the fatty-acid-synthesis pathway at, or distal to, the acetyl-CoA carboxylase step. Activities of acetyl-CoA carboxylase and fatty acid synthetase were markedly lower in ethanol-fed animals. The activity of another lipogenic enzyme, phosphatidate phosphohydrolase, was not affected by chronic ethanol feeding. These findings suggest that chronic ethanol administration has marked effects on adipose-tissue lipogenesis.

The incorporation of [myo-2-3H] inositol into phosphatidyl inositol of stimulated rat pancreas.

The 'phospholipid effect' involves agonist induced breakdown of phosphatidyl inositol (PI) or its phosphorylated derivates with increased incorporation of 32P or [myo-2-3H] inositol during resynthesis. In rat pancreas pancreozymin and bethanecol resulted in the standard dose dependent increased incorporation of 32P into PI which was paralleled by increased amylase secretion. By contrast the incorporation of [myo-2-3H] inositol into PI was significantly decreased by pancreozymin whereas bethanecol had no effect. However, pancreozymin caused a 30% decrease in labelled PI irrespective of whether it was prelabelled with 32P or [myo-2-3H] inositol. Thus in rat pancreas, pancreozymin resulted in the standard agonist induced breakdown of pre-labelled PI but inhibited the incorporation [2-3H-myo] inositol during the resynthetic phase.

The practical significance of two-dimensional deconvolution in echography.

This paper evaluates deconvolution (inverse filtering) as applied to ultrasonic imaging systems, and discusses the obstacles which are encountered employing the technique in practice. A minicomputer is used to generate artificial echo signals, simulating rf signals resulting from a set of point reflectors in a homogeneous medium, as recorded by an electronically focused group-steered linear array scanner. Two-dimensional deconvolution in combination with a Wiener noise reduction filter (i.e., a Wiener-Inverse filter) is applied to these simulated rf signals, which were contaminated with white noise. The efficacy of the Wiener-Inverse filter is defined in terms of its ability to resolve two point reflectors with a lateral spacing equal to the local -6 dB width of the ultrasonic beam. In favorable circumstances, the targets are resolved at signal-to-noise ratios (SNR) better than 20 dB, where SNR is defined as the maximum signal power divided by the average noise power level. Nonlinear effects due to quantization or signal clipping are investigated. In order to improve the resolution of an rf signal with a dynamic range of 40 dB, the input signal should be digitized at a minimum of 12 bits. The problem of signal clipping can be circumvented by oversampling. The two-dimensional Wiener-Inverse filter is defined in terms of both temporal and spatial properties of the insonification. Effects of wave diffraction give rise to a depth-dependent ultrasonic beam. As a result of a misfit of the Wiener-Inverse filter and the local properties of the ultrasonic beam, erroneous noisy texture arises in the image. Adaptation of the Wiener-Inverse filter with respect to the beam properties gives acceptable results, at the expense of a rather large computational effort.

Transducers in medical ultrasound. Part 4: Transducer safety.

Transducer safety encompasses a wide spectrum of topics. It may range from mechanical construction reliability to biological effects created by ultrasound radiation. In this Paper the electrical and acoustical safety aspects are summarized and initial experience with sterilization of echocardiographic transducers for peroperative cardiac scanning is mentioned.

Chronic ethanol feeding causes accumulation of serum cholesterol in rat pancreas.

In a previous study, a rat model of ethanol-induced pancreatic steatosis was developed in which chronic ethanol feeding resulted in a twofold increase in pancreatic cholesteryl ester content. The studies reported here were performed in order to elucidate the mechanism of this cholesteryl ester accumulation. Rats were pair fed ethanol or control diets for 3 weeks. Ethanol feeding resulted in an increased accumulation of serum cholesterol in the pancreas. Ethanol feeding also resulted in increased in vitro incorporation of labeled acetate and mevalonate into the sterol moiety of pancreatic cholesteryl ester and increased incorporation of labeled acetate into its fatty acid component. These results suggest that chronic ethanol feeding causes pancreatic cholesteryl ester accumulation by affecting exchange of cholesterol between serum and pancreatic tissue.

Computed tomography of the thymus of children under 10 years.

The CT appearance of the mediastinum of 27 patients under 10 years of age was analysed retrospectively, paying special attention to the anterior mediastinum and thymus. None of the patients had thymic disease. The purpose of the study was to record features which might be regarded as characteristic of the normal thymus. The lateral contour of the thymus was clearly seen. There were no infiltrations, but in one case there were displacements due to a prominent thymus. All the thymus glands appeared to be homogeneous. The use of contrast medium helped in distinguishing the thymus from other mediastinal structures; its use is well justified in studying the anterior mediastinum.

Increased phospholipid synthesis in the stimulated rat and human pancreas.

Stimulation of the exocrine pancreas is associated with marked changes in pancreatic phospholipid metabolism. It has been previously established that de novo synthesis of phospholipids constitutes part of this "phospholipid effect". This study has demonstrated that in vitro stimulation of the rat pancreas utilising bethanecol and pancreozymin results in increased incorporation of labelled glucose into phosphatidyl inositol and, to a lesser extent, other phospholipids, suggesting increased de novo synthesis of these compounds. However, secretin which is believed to act via a different intracellular pathway, did not exert such an effect. The relevance of this animal model is indicated by the demonstration of increased incorporation of labelled glucose into phospholipids of human pancreas stimulated in vitro by bethanecol or sincalide (the active carboxy terminal octapeptide of pancreozymin).

Alcohol causes a fatty pancreas. A rat model of ethanol-induced pancreatic steatosis.

To develop an animal mode of alcoholic pancreatic steatosis, female Wistar rats were pair fed liquid diets, containing ethanol as 36% of calories or an isocaloric amount of carbohydrate for 3 weeks. Electron microscopic examination showed lipid vesicles localized principally at the bases of pancreatic acinar cells in the ethanol-fed rats. Ethanol feeding significantly increased pancreatic content of cholesteryl ester without changing levels of other lipids. Ethanol feeding enhanced labeled acetate, palmitate, oleate, and linoleate incorporation into cholesteryl ester. Therefore, increased esterification of cholesterol may, in part, explain the observed accumulation of cholesteryl ester.

Lipoprotein lipids in renal transplant recipients of different pre-transplant etiology of renal disease. A comparison of male and female patients.

Serum and lipoprotein lipids have been compared in male and female transplant recipients with glomerulonephritis or analgesic nephropathy as etiology of pre-transplant renal disease, and a number of differences were observed. (1) Serum cholesterol and phospholipid levels were elevated in glomerulonephritis and female analgesic nephropathy, but not in male analgesic nephropathy patients. (2) Glomerulonephritis patients had normal low density lipoprotein (LDL) cholesterol levels whereas these were elevated in female and depressed in male analgesic nephropathy patients. (3) LDL phospholipid, on the other hand, was normal in male and elevated in female transplant recipients irrespective of etiology of pre-transplant renal disease, while high density lipoprotein (HDL) phospholipid levels were elevated in female glomerulonephritis patients only. Mild hypertriglyceridemia and a tendency to increased HDL cholesterol were observed in all patients. These results provide further evidence for the complexity of lipoprotein lipid abnormalities in renal disease.

Ethanol-induced changes in cardiac lipid metabolism.

The influence of ethanol on cardiac lipid metabolism has been investigated in the rat. Acute in vitro ethanol significantly stimulated the incorporation of 14C-1-acetate but not 14C-U-glucose into cardiac lipid in rats fed a diet free of ethanol for 3 weeks. Stimulation of incorporation was not uniform but was confined to the diglyceride and triglyceride fractions. This response of cardiac tissue lipid metabolism to acute ethanol was not observed in rats pair fed an isocaloric diet containing 36% of calories as ethanol. Chronic ethanol feeding significantly increased cardiac triglyceride content when compared with pair-fed controls. It also stimulated oxidation of labeled palmitate, but did not affect in vitro lipogenesis.

Influence of ethanol on pancreatic lipid metabolism.

The influence of acute exposure to ethanol on rat pancreatic lipogenesis has been investigated. Marked alterations of in vitro pancreatic lipid metabolism were found with changes compatible with increased de novo triglyceride synthesis. Ethanol in vitro stimulated (U--14C) glucose incorporation into triglyceride, but inhibited incorporation into phosphatidyl choline. Prior exposure to ethanol did not further enhance these effects on labeled glucose incorporation. One hour after feeding ethanol at a dose of 378 mg/100 g body weight, (1--14C) acetate incorporation in vitro into pancreatic lipid was significantly increased. This increase was not uniform, but was confined to the free fatty acid, triglyceride, sphingomyelin, and phosphatidyl choline fractions. Similar observations were made when pancreatic tissue from saline-fed control animals was incubated in the presence of ethanol at a concentration of 3.4 mM. Prior exposure to ethanol enhanced this stimulatory effect, and tissue from the alcohol-fed animals incubated in the presence of ethanol incorporated more acetate label into all lipid fractions than tissue from alcohol-fed animals incubated without ethanol and from saline-fed animals incubated in the presence of ethanol.

The influence of pre-transplant etiology of renal disease on lipoprotein lipids in female renal allograft receipients.

Serum and lipoprotein lipids were determined in 42 female transplant recipients and compared with age-matched and serum lipid-matched normal subjects. Eight patients had glomerulonephritis as the pre-transplant etiology of renal disease, 22 had analgesic nephropathy, 6 polycystic kidneys and 6 ureteric reflux. A number of abnormalities were observed: (i) Serum triglycerides and phospholipids were elevated in all patients. Serum cholesterol levels were increased in analgesic nephropathy, polycystic kidney and ureteric reflux, but not in glomerulonephritis patients. The serum esterified/free cholesterol ratio was reduced in all patients except those with polycystic kidneys as the pre-transplant diagnosis; (ii) All VLDL lipids were raised in transplant patients regardless of etiology of renal disease prior to transplantation; (iii) LDL lipids, cholesterol, triglyceride and phospholipid were elevated in analgesic nephropathy, polycystic kidney and ureteric reflux patients, but were normal in glomerulonephritis patients: (iv) HDL cholesterol and triglycerides were elevated in all patients regardless of etiology. HDL phospholipid levels also tended to be raised, but this was significant only in glomerulonephritis patients. Lipoprotein--lipid ratio data indicated that lipoprotein--lipid composition deviated less from normal in glomerulonephritis patients than in the other patient groups.