Calvin L. Long

Nonsuppressability of gluconeogenesis by glucose in septic patients

The contribution of alanine to the synthesis of glucose and the oxidation of alanine was evaluated in normal and septic patients using (14C)L-alanine. The data indicate that there is a twofold increase in the conversion of alanine into glucose in sepsis and, further, this increase was observed while the patients were receiving a constant glucose infusion (100 mg/min) prior to and during the single injection of (14C)L-alanine. Failure of glucose to decrease this gluconeogenic response in these septic patients clearly indicates that the controlling mechanism for glucose synthesis is modified following injury and undoubtedly plays a role in the abnormal carbohydrate metabolism observed in injury. The contribution of alanine carbon to oxidation was the same in the control and septic group as measured by the per cent of the (14C)L-alanine dose expired in 3 h. Since the control subjects received glucose continuously during the study with and without amino acids, it is clear that nutritional intake and injury has minimal effect on the oxidation of alanine. This suggests that transamination is not affected by sepsis nor is there an inhibition of pyruvate oxidation following sepsis.

Protein and energy sparing of glucose added in hypocaloric amounts to peripheral infusions of amino acids

After abdominal surgery, patients were given peripheral infusions of amino acids alone for 4 days followed by amino acids plus glucose for 4 days, or the same solutions in the reverse order. Although there was a wide variation in the response of individual subjects, the typical effect of glucose under these conditions was to reduce both nitrogen excretion (average of 2.8 g N/day) and resting metabolic expenditure (average of 110 kcal/day).

Serum Albumin Differences in Assay Specificity

Serum albumin is one of the most common parameters used in evaluating nutritional status. Three of the popular methods available for measuring serum albumin are serum protein electrophoresis and the two dye binding methods: BCG and BCP. BCG is currently the most popular method because of its simplicity, rapidity, and cost. Although electrophoretic methods are considered more accurate, BCP has shown to correlate well with electrophoresis in most cases. BCG often overestimates serum albumin levels, although its specificity can be improved by minimizing contact time with the serum sample. The average difference between BCG methods and other methods is usually 0.5-0.6 g/dL. From a quantitative standpoint, some might consider the difference in specificity of BCG versus the other two methods to be insignificant; however, from a qualitative standpoint, the difference could easily alter the interpretation of nutritional assessment parameters. Because of differences in analytical methods, serum albumin measurements should be interpreted in the context of the assay being used and the accepted normal range for that laboratory. Likewise, published studies, especially those that stratify degrees of malnutrition and/or risk of complications based on specific serum albumin levels, should specify the assay methodology utilized.

Automatic analysis of amino acids: Effect of resin cross-linking and operational variables on resolution

Abstract The definitive elaboration of the various parameters involved in the use of spherical ion-exchange resins has not been completely presented to date. This paper is an attempt to demonstrate the graded effects one may expect over a range of various temperatures, buffer pH, and the result of intermixing of resins of varying particle sizes and crosslinkages. As a result of this work, one is now in a better position to predict what will happen to a variety of ninhydrin reacting compounds that might be expected to be found in physiological fluids. A satisfactory set of conditions for an accelerated analysis of physiological fluids is presented and chromatograms are shown demonstrating resolution and peak elution time. The more difficult areas of resolution are discussed and suggestions are presented for resolving these sensitive areas based on this work.

A continuous analyzer for monitoring respiratory gases and expired radioactivity in clinical studies

A system for the continuous monitoring of gas exchange as well as 14CO2 from metabolic studies is described. The analyzer incorporates modifications over previously published systems. These modifications include accurate control of analyzer pressure for stable baselines during the long periods of measurement, accurate control of temperature, the measurement of oxygen consumption during high oxygen patient therapy, the measurement of oxygen consumption of patients on a mechanical respirator, and describes a unique flux system to calibrate the analyzer detectors. The closed system provides expired breath data for O2, CO2, and 14CO2 on critically ill patients for long periods of time without stressing the patient and without using a face mask or mouthpiece. These data allow for the calculation of daily energy expenditures of hypermetabolic patients and for the assessment of various metabolic responses with 14C substrates.

Protein turnover in advanced lung cancer patients

Understanding the extent to which changes in whole-body protein kinetics contribute to the commonly observed weight loss and decrease in lean body mass (LBM) in patients with cancer is currently obscured by conflicting reports in the literature. While several studies have reported significant increases in whole-body protein turnover (WBPT), synthesis (WBPS), and catabolism (WBPC) in patients with cancer, others have failed to confirm these observations. We have measured whole-body protein kinetics using a primed constant infusion of 15N-glycine in a homogenous group of 32 newly diagnosed advanced lung cancer patients with comparable staging and before any antineoplastic treatment, and in 19 normal healthy volunteer controls. Urinary urea and ammonia 15N enrichment was determined in individually collected urine samples obtained during the 24-hour study period and averaged for the determination of protein kinetics. During the last 6 hours of urine collection, samples were obtained hourly for determination of 15N plateau enrichment. Twenty-four-hour urinary nitrogen and creatinine excretion was determined from 24-hour pooled urine samples. Resting metabolic expenditure (RME) was determined by indirect calorimetry and LBM was estimated from deuterium oxide dilution. Age body weight, LBM, RME, and 24-hour urinary nitrogen excretion did not differ between cancer and control subjects. WBPT, WBPC, and WBPS (g/kg/d) were significantly increased in lung cancer patients. However, when the same results were expressed either per kilogram LBM or per gram 24-hour urinary creatinine excretion, WBPT, WBPC, and WBPS rates were not statistically different from those of the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption of glucose from the colon and rectum.

Abstract The absorption of glucose from the colon or rectum was evaluated in 6 adult patients. The amount and rate of expired C 14 O 2 observed when C 14 -glucose was given via the colon or rectum was similar to that observed after an intravenously administered C 14 -glucose dose. However, the specific activity of glucose isolated from the blood at intervals up to 5 hours was extremely low when compared to that isolated from blood when the C 14 -glucose dose was administered intravenously. The vast differences in blood glucose specific activity indicate the magnitude of absorption of glucose across the colon or rectal mucosa is insignificant and probably zero. The disappearance of C 14 O 2 in the breath after antibiotic intestinal treatment indicated that glucose in the colon was oxidized to CO 2 or smaller carbon residues by intestinal bacteria which was then absorbed across the intestinal wall.

A simple method for measurement of specific activity of C14-lactate☆

Abstract A simple and accurate diffusion method for the estimation of specific activity of C14-lactate is described. The method is based on the oxidation of lactate to acetaldehyde in a closed system containing a dimedon solution. Application to model systems of pure lactate and lactate in the presence of blood indicated the maximum error in a series of like samples was less than 5%. This method is limited in that it cannot detect carbon-1 radioactivity in lactate as this carbon is lost in the oxidation step to acetaldehyde.

Energy and Tissue Fuel in Human Injury and Sepsis

The loss of body weight has been a prominent feature of the response to injury or sepsis since the earliest clinical descriptions of these conditions. It was evident that the extent of weight loss tended to parallel the magnitude of the injury or sepsis. Subsequent observations revealed that the degree of weight loss is largest in males, younger adults, well-muscled individuals, and those with good previous nutrition. The weight loss is less in the female, the elderly, the poorly muscled, the nutritionally depleted. However, the underlying alterations in energy requirements and tissue fuel associated with injury and sepsis remain incompletely understood and are the subject of this discussion.