Polymer membrane sensors for continuous intravascular monitoring of blood pH.

A new type of pH sensor suitable for chronic intra-vascular implantation by virtue of its small size, flexibility, and ruggedness was constructed and evaluated. The pH-sensitive element was a thin film of an elastromeric polymer made ion permselective to proteons by adding a lipophilic, specific H+-ion carrier. This was coated onto small diameter silver wires to form sensors. In preliminary trials in anesthetized dogs, the sensors permitted continuous, accurate in vivo blood pH measurement with rapid response (less than 0.1 s).     

A simple technic for repeated collection of blood samples from mice.

A device for repeated collection of small blood samples from mice was constructed from a plastic syringe. Blood was collected into a 3.33 lambda capillary tube. Bleeding was stopped by a hemostat made from a rubber stopper. This technic allows easy collection of approximately 20 serial samples within an 8-hr period.     

Metabolism of hibernating reptiles. Changes of free amino acids in blood, liver and brain.

1. Glutamic acid showed a significant decrease during hibernation in brain cortex. This is attributed to: (a) Transformation to glutamine to detoxicate ammonia. (b) The synthesis of GABA from glutamic acid. (c) It is suggested that the enzyme GAD is active during hibernation. 2. GABA showed a significant increase in liver and brain cortex. It was absent in the blood serum. (a) The present results show that non-neural tissues contain lower GABA than neural tissues. (b) GABA may be formed locally in tissues by decarboxylation of glutamate as well as from pathways connected with tricarboxylic acid cycle. 3. Aspartic acid showed increased levels in blood serum, liver and brain cortex, the greatest increase was observed in liver. 4. A significant increase was recorded in the level of arginine in brain cortex and liver, whilst a smaller percentage increase was recorded in ornithine level. It is assumed that transformation of arginine to ornithine was depressed during hibernation.     

A refined blood collection method for quantifying corticosterone

In many rodent laboratories, blood samples are collected from rats using the tail vein nick procedure and analyzed to quantify blood corticosterone levels as an indicator of stress. The standard method of corticosterone quantification often requires the collection of a relatively large volume of blood, followed by the extraction of the blood plasma. An alternative blood sampling method requires the collection of only a drop of blood on paper (the 'drop' method), minimizing handling of the animals, and does not require plasma extraction. The authors aimed to validate the drop method of blood sampling for use in corticosterone quantification. They induced stress in rats by cerebral ischemia, collected blood samples at various intervals using both the drop method and the plasma extraction method and then quantified corticosterone by radioimmunoassay. Corticosterone levels of the ischemic rats were compared with those of sham-operated rats and those of ischemic rats that had been given metyrapone, a glucocorticoid synthesis inhibitor, prior to vessel occlusion. Blood corticosterone levels in the samples obtained from the same animal using the two different methods were highly correlated for all rats. The authors further provide a regression model that can be used to predict plasma corticosterone values from those obtained from the drop blood samples. Quantification of corticosterone from only a small drop of blood has many practical and ethical advantages and should be considered as an alternative to standard methods.     

Non-surgical cannulation of the vena cava for chronic blood collection in mature swine.

A nonsurgical cannulation technique for blood collections from mature swine was evaluated. Primiparous Yorkshire-Landrace sows (n = 6) received an indwelling jugular vein cannulae for 7 days duration. Recannulation was performed at monthly intervals for a total of 14 months. During cannulation, sows were restrained in a standing position using a rope snout snare. A 12-gauge by 10 cm needle was inserted into the jugular vein. Sterilized polyvinyl chloride tubing was advanced through the needle into the vein and a blunted 18-gauge needle and attached intermittent injection hub was inserted into the free end of the tubing. Surgical tape was used to form a butterfly on the tubing by suturing the tape to the animals' skin. Foam padding, livestock cement, and elastic tape helped to keep the tubing in position. Problems with cannulae patency and maintenance were few. No behavioral problems or systemic signs of illness were noted and necropsy examinations performed after the final cannulation revealed few abnormalities associated with chronic intermittent cannulation. This technique provides a safe, quick, effective means for multiple and repeated cannulae placement for blood collection from mature swine with minimal effects on the animal and without the risks associated with surgical techniques.     

International blood collection and storage: Clinical use of blood products

Human blood transfusion is the process of transferring blood or blood-based products from an individual into the circulatory system of another. From the theory of circulation of blood to the early practice of blood transfusion, transfusion medicine has been an important concept for many centuries. The practicality of transfusion, however, only became a possibility during and shortly after the Second World War. Today, blood and its derivatives play a critical role in worldwide health care systems, with blood components having direct clinical indications. Over the past several years worldwide organizations including the World Health Organization (WHO) have made a number of substantial improvements to the regulation of the worlds blood supply. This continuous supply plays a critical role throughout health care systems worldwide, with procedures for blood collection, processing, and storage now complex, standardised processes. As the areas of clinical validation of different disease states from blood-derived sources (i.e., disease biomarkers) move towards validation stages, the importance of controlled- and standardised-protocols is imperative.     

Standards for intravascular brachytherapy dosimetry.

The dosimetry of intravascular brachytherapy sources is quite difficult due to the small size of the sources and the close proximity at which measurements are necessary. The development of National Standards for the dosimetry of these sources is described in this paper as well as predictions of how these standards will be changed and improved upon in the future.     

Quantitative metabolomics comparison of traditional blood draws and TAP capillary blood collection

Introduction

Mass spectrometry and computational biology have advanced significantly in the past ten years, bringing the field of metabolomics a step closer to personalized medicine applications. Despite these analytical advancements, collection of blood samples for routine clinical analysis is still performed through traditional blood draws.

Objective

TAP capillary blood collection has been recently introduced for the rapid, painless draw of small volumes of blood (~?100 μL), though little is known about the comparability of metabolic phenotypes of blood drawn via traditional venipuncture and TAP devices.

Methods

UHPLC-MS-targeted metabolomics analyses were performed on blood drawn traditionally or through TAP devices from 5 healthy volunteers. Absolute quantitation of 45 clinically-relevant metabolites was calculated against stable heavy isotope-labeled internal standards.

Results

Ranges for 39 out of 45 quantified metabolites overlapped between drawing methods. Pyruvate and succinate were over threefold higher in the TAP samples than in traditional blood draws. No significant changes were observed for other carboxylates, glucose or lactate. TAP samples were characterized by increases in reduced glutathione and decreases in urate and cystine, markers of oxidation of purines and cysteine—overall suggesting decreased oxidation during draws. The absolute levels of bile acids and acyl-carnitines, as well as almost all amino acids, perfectly correlated among groups (Spearman r?≥?0.95).

Conclusion

Though further more extensive studies will be mandatory, this pilot suggests that TAP-derived blood may be a logistically-friendly source of blood for large scale metabolomics studies—especially those addressing amino acids, glycemia and lactatemia as well as bile acids, acyl-carnitine levels.