The incorporation of labeled lysine into the proteins of guinea pig liver homogenate

When C14-labeled lysine is incubated with guinea pig liver homogenate, α-aminoadipic, α-ketoadipic, and glutaric acids are formed from the lysine (1). These transformations were established by finding the radioactivity of the C14 tracer in the metabolic products. The homogenate proteins coagulated by boiling at pH 5 also contained radioactivity. The counts given by the proteins corresponded to about 0.02 to 0.03 per cent of that added as lysine; the extent of lysine incorporation into the proteins was of the same order of magnitude as Melchior and Tarver (2) had found after incubating S35-labeled methionine and Winnick et al. (3, 4) C14-labeled glycine with rat tissue homogenates. Yet we could not satisfy ourselves that the radioactivity remaining in the proteins in our experiments, although it persisted through exhaustive extraction, did not come from traces of adsorbed radioactive lysine. Some counts were found in the protein when the homogenate was boiled prior to incubation with isotopic lysine

Isolation of a peptide in guinea pig liver homogenate and its turnover of leucine

Leucine was synthesized with C14 in the carboxyl group. 10 mg. of the radioactive amino acid (DL) and 0.66 gm. (wet weight) of guinea pig liver homogenate were added to a reaction mixture containing 1.3 per cent of an amino acid mixture corresponding to the composition of casein and 0.005 M fumarate, all in a final volume of 4 ml. of isotonic saline solution(1) at pH 7.4. The reaction was carried out under oxygen for 6 hours at 38°

Incorporation in vitro of labeled amino acids into bone marrow cell proteins

Nearly all experiments on the incorporation of labeled amino acids into tissue proteins in vitro have been done on tissues whose cell structure has been partially or completely disintegrated, e.g. tissue slices, segments, or homogenates. Since cell destruction reduces or abolishes the uptake of labeled amino acids (1), it seemed worth while to carry out studies on intact cells in vitro. Bone marrow cells were found to be suitable for this purpose. The labeled amino acids used were glycine-1-C14, L-leucine-1-C14, L-lysine-1-C14, and L-lysine-6-C14

The degradation of L-lysine in guinea pig liver homogenate: formation of alpha-aminoadipic acid

A summary of the little that is known of the metabolism of lysine in animals is as follows: it is indispensable in the diet, its α-amino group does not participate in reversible transamination reaction in vivo (2), neither the L nor D form is attacked by the appropriate amino acid oxidase, certain ε-nitrogen-substituted derivatives can replace lysine in the diet and their α-amino groups are oxidized by amino acid oxidases (3, 4), no α-nitrogen-substituted derivatives yet prepared can substitute for lysine in the diet (4-6)

Incorporation in vitro of labeled amino acids into proteins of rabbit reticuloytes

Continuing our work on the incorporation of labeled amino acids into proteins (1), we have begun a study of the incorporation in vitro of C14-labeled glycine, L-histidine, L-leucine, and L-lysine into the proteins of rabbit reticulocytes. In preliminary experiments the incorporation into the hemoglobin isolated from the reticulocytes was determined. But, after it was found that plasma contains factors accelerating amino acid incorporation, it was decided to proceed as rapidly as possible toward the identification of these factors; we have, therefore, measured incorporation into the total proteins of the reticulocytes, since isolation of the hemoglobin was time-consuming. The results obtained with hemoglobin and with the total proteins are essentially the same, indicating that the other proteins of the reticulocytes incorporate amino acids at approximately the same rate as hemoglobin

Alpha-aminoadipic acid: A product of lysine metabolism

As part of a study of protein and peptide metabolism lysine was synthesized with C14 in the ε position and resolved into the L and D isomers. 10 mg. of labeled lysine dihydrochloride (either L- or D-) and 0.66 gm. (wet weight) of guinea pig liver homogenate were added to a reaction mixture containing 1.3 per cent of an amino acid mixture corresponding to the composition of casein except for lysine and 0.01 M α-ketoglutarate, all in a final volume of 4 ml. of isotonic saline solution.(1) The reaction was carried out under oxygen for 6 hours at 38°

A peptide fraction in liver

We reported in a preliminary communication (1) the isolation of a peptide fraction from guinea pig liver. The following points of interest appeared at once: many different amino acids were obtained on hydrolysis; the peptide fraction contained most of the indispensable amino acids, which indicated that it probably is important in protein metabolism; when guinea pig liver homogenate was incubated with C14-labeled glycine, leucine, or lysine, these were rapidly incorporated into this peptide fraction, which is further evidence that it is metabolically active; the peptide fraction had not been described hitherto; a fraction containing one or more large peptides can be separated from so complex a mixture as liver homogenate by starch chromatography

The uptake in vitro of C14-labeled glycine, L-leucine, and L-lysine by different components of guinea pig liver homogenate

We have reported (1) that L-lysine labeled with C14 can be incorporated into the proteins of guinea pig liver homogenate under two different conditions. In the one case the enzyme used was the whole homogenate, the optimum pH was near 6.2, there was an obligatory requirement of calcium, and the incorporation was independent of oxygen. This set of conditions is designated below as the “acid calcium” condition. In the other case the enzyme system was the precipitate obtained by centrifuging the homogenate diluted 15-fold with Ringer’s solution at 2500 X g, the optimum pH was near to 7.3, the reaction was accelerated a little by calcium but the presence of calcium was not obligatory, and the incorporation was a little less under nitrogen than under oxygen. This set of conditions is designated below as the “alkaline” condition

Multi-task multiple kernel machines for personalized pain recognition from functional near-infrared spectroscopy brain signals

Currently there is no validated objective measure of pain. Recent neuroimaging studies have explored the feasibility of using functional near-infrared spectroscopy (fNIRS) to measure alterations in brain function in evoked and ongoing pain. In this study, we applied multi-task machine learning methods to derive a practical algorithm for pain detection derived from fNIRS signals in healthy volunteers exposed to a painful stimulus. Especially, we employed multi-task multiple kernel learning to account for the inter-subject variability in pain response. Our results support the use of fNIRS and machine learning techniques in developing objective pain detection, and also highlight the importance of adopting personalized analysis in the process.Comment: International Conference on Pattern Recognition (ICPR

Migraine attacks the Basal Ganglia

<p>Abstract</p> <p>Background</p> <p>With time, episodes of migraine headache afflict patients with increased frequency, longer duration and more intense pain. While episodic migraine may be defined as 1-14 attacks per month, there are no clear-cut phases defined, and those patients with low frequency may progress to high frequency episodic migraine and the latter may progress into chronic daily headache (> 15 attacks per month). The pathophysiology of this progression is completely unknown. Attempting to unravel this phenomenon, we used high field (human) brain imaging to compare functional responses, functional connectivity and brain morphology in patients whose migraine episodes did not progress (LF) to a matched (gender, age, age of onset and type of medication) group of patients whose migraine episodes progressed (HF).</p> <p>Results</p> <p>In comparison to LF patients, responses to pain in HF patients were significantly lower in the caudate, putamen and pallidum. Paradoxically, associated with these lower responses in HF patients, gray matter volume of the right and left caudate nuclei were significantly larger than in the LF patients. Functional connectivity analysis revealed additional differences between the two groups in regard to response to pain.</p> <p>Conclusions</p> <p>Supported by current understanding of basal ganglia role in pain processing, the findings suggest a significant role of the basal ganglia in the pathophysiology of the episodic migraine.</p