Nylon Tube Research Articles

Two simple tools for preparing iridium-192 wire for clinical use.

192Ir wire is supplied by Amersham International either as hairpins (or single pins) which are 60 mm long and 0.6 mm in diameter or as 0.5 m lengths of 0.3 mm diameter wire. One of its advantages in interstitial therapy is that it may be cut to the required length. A tool for cutting hairpins has been described by Collins (1975). This note describes a device which is perhaps simpler and has the advantage that it is easy to cut the pins to different leg lengths. Two commercial devices exist for loading the 0.3 mm wire into nylon tubing, but neither is ideal. The TEM loader (a commercial version of that described by Darby et al (1972)) is very expensive and the 192Ir wire may fail to feed correctly if the instrument is not perfectly aligned, although such occasions are now rare following a recent redesign. The Amersham loader (Amersham International—Type N.410), although inexpensive, is difficult to use (but we understand that Amersham International are currently redesigning their loader). This note describ...

Tubular orthoses.

A method of constructing orthoses and other patient devices using nylon tubing and clip-together standard components is described. This permits the rapid assembly of custom orthoses that can be evaluated before prescription in a clinical setting. These orthoses have been successfully used for the control of thoracic spinal flexion, hip abduction, elbow extension, shoulder abduction, cervical spine stabilization and pressure sore relief. Advantages over existing orthoses include reduced weight, improved comfort and cosmesis, low cost and increased speed of provision. Examples of these orthoses are shown, together with details of their structure, function and clinical results.

Nylon tubing as an affinity matrix in the purification of acetylcholine receptors and immunosorption studies.

Nylon tubing as an affinity matrix in the purification of acetylcholine receptors and immunosorption studies.

Analysis of serum creatinine using an immobilized enzyme nylon tube reactor incorporating a four-enzyme system.

Ginman et al. ( l) recently described the use of a single nylon reactor with four immobilized enzymes for the analysis of creatinine in urine. The tube was incorporated in a continuous flow system. Good correlation with the Jaff6 method has been obtained with a manual technique employing the same enzymes in solution (r = 0.992). The advantages of using enzymes for the quantitation of creatinine over Jaff6 methods are precision, high specificity, simplicity, and speed of analysis. However, when the method was applied to the analysis of serum, it was found that direct sample application of serum gave poor results, probably because of interference by serum proteins or by nonspecilic NADH-consuming reactions. Pre-

A standardized monitor for the control of ethylene oxide sterilization cycles.

The resistance of spores of B. subtilis var. niger produced in liquid synthetic medium and exposed to ethylene oxide on a nylon surface, has been shown to the almost identical to that for spores produced on a traditional solidified complex medium with exposure to the sterilant on aluminium foil. The use of short lengths of nylon tube as carriers allowed easy production and handling, with self-protection of the spore-bearing surface. Addition of a dye provided visual evidence of inoculation without affecting resistance to ethylene oxide. Such a monitor is suitable for use as a standardized biological challenge in routine ethylene oxide sterilization cycles.

The use of an immobilized enzyme nylon tube reactor incorporating a four enzyme system for creatinine analysis.

A single immobilized enzyme nylon tube reactor was produced incorporating a four enzyme system for the analysis of creatinine. The enzyme activity ratios in the coupling solution used to prepare the reactor were found to be of extreme importance in governing the activity of the latter. The reactor was incorporated into a continuous flow analysis system used to assay creatinine in urine samples and the results were correlated with a manual technique employing the same enzyme system in solution. The precision, correlation, high specificity, simplicity, and speed of the analysis were concluded to be factors in favor of the method's suitability for urine creatinine determinations.

Minimization of Catalase Interference in Glucose Determinations with Immobilized Glucose Oxidase

Abstract Catalase, co-immobilized with glucose oxidase in an open, nylon tube, can decompose hydrogen peroxide and reduce the sensitivity of continuous flow glucose determinatinos. Millimolar concentrations of sodium azide display mixed-type noncompetitive inhibition of catalase. Because of this, the assay sensitivity can be improved by a factor of four or more by adding azide. Azide does not affect the Trinder/peroxidase color-forming reaction, but does inhibit glucose oxidase noncompetitively with an inhibition constant of 18 mM. Significant amounts of catalase are indicated by a nonlinear relationship between instrumental response and reactor length. Upon addition of 1 mM azide to the reaction manifold, the response becomes directly proportional to the reactor length (0-50 cm).

Nylon tube linked acetylcholine receptor: a tool for affinity isolations and immunosorption.

We have covalently coupled acetylcholine receptor and other proteins to the inner surface of nylon tubes and employ these affinity tubes in binding assays and for chromatographic purposes. Here we describe two applications: (i) The concentration determination of toxins and antibodies directed against the acetylcholine receptor, and (ii) the isolation and chromatography of specific immunoglobulins.

Activation of nylon by alkaline glutaraldehyde solution for enzyme immobilisation

Nylon tube was directly activated by alkaline glutaraldehyde solution. PEI was utilised as a spacer molecule. Glucose oxidase was immobilised to the nylon tube after reactivating the spacer molecules with glutaraldehyde. On immobilising glucose oxidase there was more protein binding and higher immobilised enzyme activity when compared to immobilised enzyme tube activated by triethyloxonium salt. The optimal condition for direct glutaraldehyde activation of nylon was incubation with 18.5% (w/v) glutaraldehyde in 0.12M borate pH 9.0 for 15 min at 90 °.

A stopped-flow instrument for reaction-rate measurements with immobilized enzymes

A stopped-flow instrument that provides direct and continuous monitoring of reactions catalyzed by enzymes immobilized inside open tubes is described. The instrument allows complete reaction progress curves to be obtained during a single experiment. Because the reaction occurs under static conditions, the kinetics are controlled only by diffusion and the inherent enzyme reaction rate. The kinetics constants for lactate dehydrogenase covalently bound inside nylon tubing and in aqueous solution were determined and compared.

Kinetics of yeast alcohol dehydrogenase and its coenzyme coimmobilized in a tubular flow reactor

Yeast alcohol dehydrogenase and nicotinamide adenine dinucleotide (NAD) were coimmobilized, with covalent attachment, to the interior surface of a nylon tube. The NAD was attahed at the N(6) group of the adenine moiety; an NAD derivative was prepared and attached to free carboxyl groups at a partially hydrolyzed nylon surface. The enzyme was attached, through glutaraldehyde residues, to free amino groups on the surface. Kinetic studies were carried out in which the reduced NAD was recycled by means of phenazine ethosulfate and 2,6-dichlorophenol indophenol. The reaction was studied over a range of flow rates and ethanol concentrations. The variation of rate with flow rate suggested that there was little diffusion control with respect to ethanol and that there was no observable inhibition by the reaction products. These conclusions were confirmed by evidence based on dimensionless parameters for the reaction and by direct inhibition experiments. The apparent Michaelis constant was lower than when only the enzyme was immobilized, suggesting that the immobilized enzyme-coenzyme system is of high efficiency. Overall rates of reaction were lower than when there was saturation with NAD. The tube showed no measurable loss of catalytic activity over a period of one month.

Analytical applications for routine use with immobilized enzyme nylon tube reactors

Analytical systems have been developed for the automated assay of urea, uric acid, glucose, pyruvate, lactate, creatinine, creatine, glycerol, triglycerides and cholesterol. These analytical systems consist of hollow tubes of polymeric nylon to the insides of which specific enzymes are covalently immobilized and analysis is performed by perfusion of the sample through the reactors at a rapid rate of 50–60 tests per hour. The design and development of these reactors that show high specificity and operational dependability, as demonstrated by detailed clinical trials, is discussed. All the metabolites mentioned above can be detected by the linear range clinically relevant in these reactors, which are very stable during use in continual analysis and storage.

PH dependence of free and immobilized yeast alcohol dehydrogenase kinetics.

A study was made of the influence of pH on the reaction between NAD and ethanol, catalyzed by yeast alcohol dehydrogenase, both in free solution and attached to the inner surface of a nylon tube. A new least-squares analysis of the results has been devised; it is simpler to apply and is more realistic than those previously employed. Analysis of the results for the free enzyme indicated that the free enzyme has two active ionizing groups having pK values of about 6.6 and 8.8. These pK values undergo only small changes when the enzyme is bound to NAD and when it is bound to both NAD and ethanol. With the immobilized enzyme and saturating concentrations of ethanol the rates went through a maximum as the pH was varied from 6.5 to 10.0. With saturating concentrations of NAD there was a steady increase in rate, with no falling off at pH 10. Immobilization generally brought about an increase in the pK values. These increases are attributed partly to a residual negative surface charge which attracts the leaving H+ ions. They are also attributed partly to the formation in the reaction of H+ ions, which cause the local pH to be lower than that in the bulk solution. This effect is more important with saturating NAD ions, since the buffer anions will then be less mobile and less able to mediate the movement of protons.

Double-lumen flow-through swivel for chronic experiments with unrestrained monkeys

Two modifications of a flow-through swivel are described for prolonged infusions into and simultaneous blood-sampling from chronically implanted catheters of large, unrestrained animals, e.g., rhesus monkeys. In addition, both offer easy access to the catheters proximal to the swivel and to the lumen of the reinforced nylon tubing which connects the animal to the swivel.

Evaluation of the Technicon bound uricase method for the determination of uric acid in urine.

We have evaluated the Technicon bound uricase method for the determination of uric acid in urine with the AutoAnalyzer II. The general analytical characteristics of the method, and the effect of urine on the immobilized uricase nylon tube reactor were investigated. The method was found to be a linear up to 7.0 mmol/l with aqueous standards and up to 5.0 mmol/l with urine samples. Between-days imprecision had a coefficient of variation (CV) of 1.6% for values of about 1.2 mmol/l, and 0.8% for values above 3.5 mmol/l. Within-run imprecision gave a CV of 0.7% for values of 1.07 and 2.95 mmol/l and a CV of 0.4% for a value of 4.77 mmol/l. The mean analytic recovery was 99.1% (range 93.8-103.0%). The sample interaction was 0.9%. The correlation with the phosphotungstate method and the manual Dutch standard method was good, but the enzymatic values were 20% lower than the phosphotungstate values. Storing the immobilized uricase nylon tube reactor at 4 degrees C, when not in use, prolonged the lifetime by nearly 50%. Urine samples were not different from aqueous uric acid standards in their effect on the stability of the uricase nylon tube reactor.

Affinity chromatography and immunosorption with acetylcholine receptor attached to nylon tubes.

Nylon-linked proteins were used for affinity trapping and chromatography. As representative examples purified acetylcholine receptor, alpha-cobratoxin and bovine serum albumin were coupled to the activated matrix to serve as biospecific ligands. In particular, acetylcholine receptor was coupled without significant loss of biochemical properties. The resulting affinity tubes bind receptor-specific ligands including immunoglobulins and thus can be used for affinity-chromatographic purposes and immunoassays.

Polysaccharide derivatives as coats for nylon tube urease

Urease was immobilized on O-alkylated nylon tubes coated with polyaminated derivatives of starch or dextran. The specific activity of the enzyme coil and the relative stability of the immobilized enzyme, compared with immobilized urease derived from other nylon tube modifications, were enhanced. Also, the nonspecific binding of urease to O-alkylated nylon tubes was virtually eliminated by the coating process.

Uricase immobilized onto nylon tube for use in automated analysis of serum urate

Uricase is immobilized onto glutaraldehyde-activated nylon tube. Immobilized uricase tube is incorporated into a continuous flow automated analyzer for assaying blood urate. The immobilized enzyme shows good storage and operational stability and the assay system compares favorably with an established method.

Reinnervation of teeth, mucous membrane and skin following section of the inferior alveolar nerve in the cat

The reinnervation of teeth, mucous membrane and skin has been investigated in the cat following section of the inferior alveolar nerve. Evidence for regeneration of sectioned fibres and for sprouting of unsectioned nerves supplying adjacent tissues (collateral sprouting) was sought. In some experiments the cut nerve ends were reapposed whilst in others the central stump was either covered with an acrylic cap or sealed inside a nylon tube. The jaw opening reflex evoked by electrical stimulation of canine tooth pulp was abolished by inferior alveolar nerve section but returned within 3–9 weeks with a raised threshold and increased latency. After re-apposition or acrylic capping, some sectioned nerves regenerated but, compared with normal, they had decreased conduction velocities, greater variation in their mechanoreceptor fields and produced smaller compound action potentials in the teeth. There was little evidence of collateral sprouting. The nylon tube completely blocked regeneration but the denervated tissues were reinnervated by collateral sprouting. Fibres supplying tooth pulp were present in the ipsilateral mylohyoid, the ipsilateral and contralateral lingual nerves and the contralateral inferior alveolar nerve. Except for the ipsilateral lingual nerve, these nerves do not normally include pulpal fibres. Partial reinnervation of skin and mucous membrane occurred and this was derived from the ipsilateral mylohyoid, lingual and buccal nerves and the contralateral inferior alveolar nerve.

The effects of substrate flow-rate on immobilized urease assays

Urease (urea aminohydrolase, EC 3.5.1.5) has been immobilized on o-alkylated nylon tubes in an enzymatically active form. The measured activity of the enzyme coil has been shown to be dependent on the flow rate of substrate through it. The apparent K m decreased and V increased as flow rates were increased. It is suggested that diffusional control is responsible for these observations. Their implications in flow-through immobilized enzyme analyses are discussed.