Biomedical subjects

S R Petersen

Publications and source records attributed to S R Petersen.

At least 37 records · Page 2Linked to original sources

PubMed1995

Plasma levels of insulin-like growth factor binding protein-3 in acute trauma patients.

Insulin-like growth factors (IGFs) are a family of polypeptides that regulate cell growth. Their action and bioavailability are modified by binding proteins such as IGF binding protein-3 (IGFBP-3). Plasma IGFBP-3 level was found to be growth hormone (GH)-dependent, which makes detection of IGFBP-3 useful in the evaluation of GH secretion. In the early catabolic flow phase of severe injury, when plasma levels of GH and IGF-1 are low versus uninjured levels, the role of IGFBP-3 has not been investigated. We have measured basal levels of these polypeptide hormones in 16 adult (13 men and three women aged 47 +/- 7 years) severely injured (Injury Severity Score, 32 +/- 2), hypermetabolic resting energy expenditure [REE] to basal energy expenditure [BEE] ratio, 1.30 +/- 0.05), ventilator-dependent, multiple-trauma patients within 48 to 60 hours of injury when the patients were receiving maintenance fluids without calories or nitrogen. These basal values were compared with those of 16 age-matched postabsorptive normals. In the catabolic flow phase of injury, plasma levels of GH, IGF-1, and IGFBP-3 were significantly reduced by 50%, 46%, and 45%, respectively. There was a significant linear inverse relationship between IGFBP-3 and age and also a positive correlation between IGFBP-3 and IGF-1 in both control and injured subjects. The ratio of IGFBP-3 to IGF-1 was not changed in trauma victims. Measurement of plasma IGFBP-3 levels has potential as a marker for monitoring GH therapeutic efficacy.

Adult↗

PubMed1995

Pulsatile nature of growth hormone levels in critically ill trauma victims.

BACKGROUND: Circulating growth hormone (GH) levels in normal persons fluctuate widely because of pulsatile GH secretion. It is not known whether this pulsatile nature and rhythmicity exist in severe injury. These data become necessary to decide the timing of supplementary GH administration for its optimal utilization. The purpose of this study was to investigate the GH circadian variation with respect to that of insulin-like growth factor-1 (IGF-1), insulin, C-peptide, and cortisol in the early flow phase of injury. METHODS: Plasma GH, IGF-1, insulin, C-peptide, and cortisol levels were measured at 1-hour intervals during 24 hours (8 AM to 8 AM) in 10 severely injured adults with multiple trauma during the early catabolic flow phase 24 to 48 hours after injury, when patients received maintenance fluids without calories or nitrogen. RESULTS: The 24-hour integrated GH concentration is not different from either 12-hour mean diurnal or 12-hour mean nocturnal or mean 8 AM GH concentration. Pulsatile GH bursts persist in injured patients during both day and night. Pulsatile bursts do not exist for IGF-1, insulin, and C-peptide. The plasma levels of cortisol show time-dependent daily maximum and minimum levels. CONCLUSIONS: Pulsatile GH bursts persist in injured patients but less frequently than seen in normal persons. The time of bolus administration of GH to augment the anabolic GH action in patients with trauma does not matter; however, for convenience morning administration may be preferable for patients in the intensive care unit.

Activity Cycles↗

PubMed1995

Altered brain and muscle amino-acid levels due to remote injury during glutamine supplementation.

Glutamine (GLN) has aroused considerable interest among clinicians and nutritionists after studies demonstrated conclusively profound GLN depletion during critical illness. Although the brain plays an important role in GLN metabolism, little is known concerning changes in cerebral handling of GLN following injury. We have evaluated in a rat trauma (bilateral femur fractures) model, the nutritional efficacy of GLN-rich diet and the remote injury-induced changes in amino-acid (AA) contents of brain and muscle tissues. Both control and traumatised rats were starved for 2 days and then pair-fed for 4 days, either a basic liquid diet (BioServ # F1259) or an isonitrogenous test diet which contained the same basic diet from which 10% nitrogen (N) was replaced by GLN-N. Protein efficiency ratio as well as plasma levels of anabolic growth hormone and insulin did not change due to GLN-enriched diet. Remote injury-induced changes in GLN and glutamic acid (GLU) during GLN-rich diet were minimal in brain tissues; whereas GLN levels were decreased in plasma and muscle, GLU levels were increased in plasma and decreased in muscle tissues. The AA levels of brain tissues, in general, were maintained within narrow limits during GLN supplementation in control and injured rats. An increased influx of tryptophan and increased synthesis of the neurotransmitter serotonin were suggested due to GLN-enriched diet.

Journal Article↗

PubMed1995

Adjuvant recombinant human growth hormone stimulates insulin-like growth factor binding protein-3 secretion in critically ill trauma patients.

The early catabolic phase of severe injury is associated with acute growth hormone (GH), insulin-like growth factor-1 (IGF-1), and insulin-like growth factor binding protein-3 (IGFBP-30 deficiency. The metabolic half-life of circulating IGF-1 is prolonged by its binding to IGFBP-3. The role of this binding protein in nutritionally repleted multiple-injury patients has not been previously evaluated. We have measured plasma levels of these polypeptides and nitrogen (N) balance in 18 adult (15 males/3 females; mean age, 45 years), severely injured, hypermetabolic, and highly catabolic trauma patients within 48 to 60 hours after injury, when they were receiving maintenance fluids without calories or N and during 6 days of total parenteral nutrition (TPN). Before instituting TPN, the patients were randomized to receive (group H, n = 9) or not to receive (group C, n = 9) daily recombinant human growth hormone (rhGH), 0.15 mg/kg IM. Adjuvant rhGH significantly increases plasma levels of GH, IGF-1, IGFBP-3, and insulin. In addition, it shows better improvement in N balance. The bioavailability of IGF-1 is increased, as indicated by the decrease in IGFBP-3:IGF-1 ratio. A significant correlation between IGF-1 and IGFBP-3 levels is present in the trauma patients who received TPN and rhGH. A GH/IGF-1/IGFBP-3 axis that closely regulates the metabolic status of the patient is established in trauma.

Adult↗

PubMed1994

Influence of diet with or without amino acids on polyamine excretion in multiple trauma victims.

Elevated levels of urinary polyamines (PA) in severely injured trauma patients are further enhanced by total parenteral nutrition (TPN) that contains both glucose and amino acids (AAs). Since TPN solutions contain arginine, the AA precursor of PA, it is not certain whether the increased urinary PA are due to this substrate. Nutritional factors can evidently modify PA metabolism. We measured the daily excretion of the PA, putrescine (PU) and spermidine (SD) in 18 multiply injured (injury severity score [ISS], 32 +/- 2), hypermetabolic (resting energy expenditure [REE]/basal energy expenditure [BEE], 1.41 +/- 0.06), and highly catabolic (daily N loss, 17.2 +/- 1.8 g N/d) acute trauma patients for 5 days in the early flow phase of injury. The patients were fed only maintenance fluids without calories or nitrogen for the first day 60 to 72 hours after injury, and then were randomized to receive glucose alone ([GLUC] 4.1 mg/kg/min, 80% measured REE, n = 8) or the same amount of glucose with AAs (TPN, 275 mg N/kg/d, n = 10) for the following 4 days. There was no significant difference in the enhanced daily PA excretion either in the free or acetylated form between the two dietary regimens. The addition of AAs in the TPN mixture did not seem to further stimulate PA metabolism in the trauma patients. The source of the nutrient content of the diet appears to be important for enhancing total PA excretion in critically ill patients.

Adolescent↗

PubMed1994

Enhancement of protein synthesis efficiency in parenterally fed trauma victims by adjuvant recombinant human growth hormone.

In the early catabolic phase of severe injury, conventional nutritional support is inadequate to reverse negative nitrogen balance and an anabolic stimulus may be beneficial. The utilization efficiency of body energy sources after injury could be improved by adjuvant recombinant human growth hormone (rhGH) therapy. We measured the protein kinetic response to exogenous rhGH in trauma patients fed parenterally (TPN). Severely injured (mean ISS, 31 +/- 2), highly catabolic (mean nitrogen loss, 19 +/- 2 g/day), and hypermetabolic (mean BEE/REE, 1.41 +/- 0.05), adult (mean age, 46 +/- 5 years), multiple trauma victims (n = 20, 17 men/3 women) were investigated. Rates of whole-body protein kinetics (turnover [WBPT], synthesis [WBPS], breakdown [WBPB], and protein synthesis efficiency [PSE]--the fraction of nitrogen turnover utilized for protein synthesis) were measured using a primed-constant infusion of 18N glycine 48 to 60 hours after injury when the patients were receiving only maintenance fluids without calories or nitrogen. The patients were then fed glucose-based TPN (1.1 x REE; 250 mg N/kg/day) and randomized to receive or not to receive rhGH. Group H (n = 10) received daily rhGH (0.15 mg/kg/day, Somatropin, Genentech, Inc.) intramuscularly at 8 am and group C (n = 10) received only the vehicle of infusion. Protein kinetic measurements were repeated at the end of 7 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Nutritional influence on the recovery of 14CO2 in critically ill trauma patients.

Several factors, including age, nutritional and metabolic status, and underlying pathological conditions, should be considered in estimating the correction factor for labeled CO2 retention. We have evaluated the nutritional influence of this correction factor in a group of severely injured (injury severity score = 33 +/- 5), hypermetabolic, and highly catabolic adult trauma patients. Primed-constant infusion of NaH14CO3 was used, and the breath 14CO2 radioactivity was measured. The experiment was conducted once in the fasting condition during the early catabolic "flow" phase of injury and again during and after a week of intravenous feeding. The mean value of the 14CO2 recovery (85.2 +/- 2.7%) in the basal fasting condition was higher than the value of 81% commonly used in normal subjects. During intravenous nutritional support the recovery was 100.8 +/- 1.7%. Recovery of tracer increased linearly with O2 uptake and CO2 production. The linear expression obtained between recovery and CO2 production could estimate the recovery within 3% in trauma patients, and that obtained by multiple regression with CO2 production and O2 uptake would predict the recovery within 1.5%.

Adult↗

PubMed1994

Altered lipid kinetics in adjuvant recombinant human growth hormone-treated multiple-trauma patients.

Adjuvant recombinant human growth hormone therapy during the postinjury period may improve the efficiency of utilization of body energy stores. In a group of 20 severely injured highly catabolic hypermetabolic adult multiple-trauma victims, we have investigated the basic lipid kinetics of trauma (study I) and its modification after 7 days of intravenous feeding (total parenteral nutrition) with (group H, n = 10) or without (group C, n = 10) daily rhGH (0.15 mg somatotropin.kg-1.day-1) intramuscular injections (study II). Whole body lipolysis rate (2-stage primed constant infusion of 10% glycerol), substrate net oxidation rates (indirect calorimetry), and plasma levels of hormones were determined. Compared with the control group (group C) the treatment group (group H) showed significantly (P = 0.006) enhanced rates of lipolysis and free fatty acid reesterification (10 +/- 2 to 18 +/- 2 kcal.kg-1.day-1, P = 0.05). As a function of resting energy expenditure (REE), a trend of increased net glucose oxidation [32 +/- 10 vs. 56 +/- 7% REE, not significant (NS)] and decreased fat (40 +/- 8 vs. 25 +/- 5% REE, NS) and protein oxidation rates (28 +/- 2 vs. 19 +/- 2% REE, P = 0.007) were also indicated. The simultaneous operation of increased lipolytic and reesterification processes may allow the adipocyte to respond rapidly to changes in peripheral metabolic fuel requirements in injury.

Chemotherapy, Adjuvant↗

PubMed1993

Protein and glucose fuel kinetics and hormonal changes in elderly trauma patients.

We investigated the responsiveness of whole-body protein and glucose kinetics to severe trauma and the role of regulatory hormones in the early catabolic "flow phase" of injury in a group of patients ranging in age from 19 to 85. Energy metabolism (indirect calorimetry), protein kinetics (primed-constant infusion of [15N]glycine), glucose metabolism (primed-constant infusion of [U-14C]glucose and [6-3H]glucose), and circulating hormone levels were measured during basal conditions within 48 to 60 hours after injury when the patients were receiving maintenance fluids without N or calories. Experimental data were analyzed as two groups (young, age 18 to 59, and elderly, age 60 to 85) and also as linear function of advancing age. The geriatric trauma (GT) group lost less N (11.9 +/- 1.3 v 17.7 +/- 1.7 g N/d, P = .025) than the younger group, mainly due to a significantly decreased whole-body protein breakdown (WBPB) rate. Despite a similar production and oxidation rate of glucose, hyperglycemia was more exaggerated in the elderly group. Advancing age resulted in significant positive correlations with plasma glucose levels and negative correlations with circulating growth hormone levels, urinary nitrogen loss, and protein turnover. These results suggest an age- and body composition-related reduced energy and protein metabolic response to severe trauma in elderly individuals.

Adolescent↗

PubMed1993

Relative nutritional efficacy of arginine and ornithine salts of alpha-ketoisocaproic acid in traumatized rats.

The relative dietary efficacy of arginine alpha-ketoisocaproate (AKIC) and ornithine alpha-ketoisocaproate (OKIC) is evaluated in a rat (Sprague-Dawley) trauma (bilateral femur fracture) model. Both control and traumatized rats were starved for 2 d and then pair-fed for 2 or 4 d one of three liquid diets: diet 1 was a basic casein diet; diets 2 and 3 were the basic diet in which 10% of nitrogen was replaced by AKIC or OKIC nitrogen, respectively. Irrespective of the diet, the protein-efficiency ratio, defined as the gain in body weight per grams nitrogen consumed, was 27% less in traumatized rats than in control rats. More improvement in apparent nitrogen balance, particularly in traumatized rats, was seen with the AKIC supplement. Plasma amino acid patterns demonstrated stimulation of net protein synthesis with AKIC and not with OKIC. Dietary supplementation with AKIC may be beneficial to promote nitrogen economy in trauma victims.

Amino Acids↗

PubMed1993

Is the metabolic response to injury different with or without severe head injury? Significance of plasma glutamine levels.

Acute brain injury is the single largest cause of trauma center deaths. Injury that does not involve the brain directly can lead to a cascade of changes in neuroendocrine system function. In order to evaluate the effect of head injury in severely traumatized patients on the response of body fuel mobilization and utilization, 42 adult patients were studied in the early "flow" phase of injury in the fasting state. They were divided into two groups: (1) multiple trauma patients without head injury (MI group, n = 21); and (2) multiple trauma patients with severe head injury (HMI group, n = 21). This enabled evaluation of the influence of injured brain on the general response to body injury. Kinetic measurements of protein (primed-constant infusion of 15N glycine), glucose (14C and 3H isotopic glucoses), fat (two-stage glycerol infusion), and energy metabolism (indirect calorimetry) were made along with hormone and substrate determinations. The results of this integrated approach demonstrated similar hormonal and metabolic changes between these two groups of patients. However, hepatic glucose production and whole body lipolysis rates were significantly decreased in HMI patients. In addition, hyperglycemia and hypoglutaminemia were more pronounced in injured patients with associated head injury. Glutamine release, which forms a significant net release of brain amino acids in normal subjects may be impaired in HMI patients. Associated brain injury appears to moderate the systemic effect of trauma.

Adolescent↗

PubMed1992

Acute IGF-1 deficiency in multiple trauma victims.

The circulating levels of IGF-1 in the catabolic flow phase of injury were measured in multiple trauma victims once before nutritional support and again after 4 days of intravenous feeding. The hypermetabolic and highly catabolic state of injury is characterized by a diminished level of IGF-1 along with increased levels of stress hormones. Inverse relationships of adiposity and aging on IGF-1 levels are seen both in injured and uninjured subjects. Feeding could restore the IGF-1 levels in non-obese, young patients but it is delayed in obese or elderly subjects. This diminished responsiveness to feeding of IGF-1 hormone deficiency in obese and elderly subjects should be taken into consideration in their post-trauma treatment and may warrant adjuvant administration in these types of patients.

Journal Article↗

PubMed1992

Steroid use is associated with pneumonia in pediatric chest trauma.

A review of pediatric trauma focused on pediatric chest injuries was performed at a trauma center specializing in neurologic trauma. Eighty of 342 (23%) pediatric trauma patients admitted to the center had chest injuries. Age, gender, mechanism of injury, magnitude of injury, incidence of pulmonary infection, chest tube usage, endotracheal intubation, steroid or antibiotic usage, morbidity, and mortality data were reviewed. Sixteen of 78 children (20%) with chest injuries developed pulmonary infections and were compared with the noninfected group. Patients with pneumonia had a higher morbidity with significantly longer mean hospital stay (43.0 vs. 12.7 days; p = 0.001), duration of intubation (8.4 vs. 1.5 days; p = 0.001), and total days with chest tubes, (2.2 vs. 1.4 days; p = 0.02). Pneumonia was significantly associated with longer mean duration of steroid usage (6.4 vs. 0.8 days; p = 0.0001). Duration of steroid administration for the treatment of concomitant brain injury was a significant independent risk factor for the occurrence of pneumonia.

Adolescent↗

PubMed1992

Effect of high velocity resistance training on peak torque, cross sectional area and myofibrillar ATPase activity.

The purpose of this investigation was to determine the effect of high velocity resistance (HVR) training on peak torque (PT), cross sectional area (CSA) and myofibrillar ATPase activity of the knee extensors. HVR training was performed in a circuit on hydraulic exercise equipment, 4 times a week for 5 weeks at an angular velocity of approximately 3.14 rad.s-1. Knee extension PT was determined on a Cybex II isokinetic dynamometer and CSA of the quadriceps femoris muscle was assessed using computer tomography (CT) scanning. Muscle biopsies were obtained from the lateral quadriceps muscle and were analyzed for myofibrillar ATPase activity. Knee extension peak torque was significantly increased at 1.57, 2.09, 3.14, 3.66 and 4.19 rad.s-1. Myofibrillar ATPase activity and CSA was also significantly increased after HVR training. These findings showed that short-term high velocity resistance training enhances the in vivo torque/velocity curve especially at fast angular velocities and these changes are partly attributed to an increase in muscle CSA and activity of myofibrillar ATPase.

Adaptation, Physiological↗

PubMed1991

Physiological adaptations to concurrent endurance training and low velocity resistance training.

This study investigated the effects of concurrent endurances and low velocity resistance training (LVR) on measures of strength and aerobic endurance. One group (ES) performed concurrent endurance training 3 days a week and LVR training on alternate days, 3 days a week for 12 weeks. The other group (S) performed only LVR training 3 days a week for 12 weeks without any endurance training. Measurements and increases in training volume were made every three weeks in both groups. Group ES exhibited increases in submaximal exercise responses after 3, 9 and 12 weeks (p less than 0.05). Knee extension peak torque and total work as well as cross-sectional area of quadriceps femoris were significantly increased after 6 and 9 weeks of training in both groups. These findings indicate that no significant differences in strength gains were observed between subjects performing concurrent endurance and resistance training or resistance training only. However, the time-course of adaptations between groups was somewhat different.

Adaptation, Physiological↗

PubMed1991

Delayed diagnosis of cervical spine injuries.

Over a 32-month period, the cases of all patients with multiple injuries on whom cervical spine roentgenograms (CSRs) were obtained during blunt trauma evaluation in a trauma center were reviewed to determine the incidence, outcome, and clinical consequence of delayed diagnosis of cervical spine injuries. A total of 1,331 patients had CSRs following blunt injury. Sixty-one (4.6%) of the patients had documented cervical fractures or dislocations. The patients were seriously injured (mean Trauma Score, 12; mean Glasgow Coma Scale score, 11; and mean Injury Severity Score, 30.3). Eleven of the patients died in the trauma room; 9 with fatal atlantoaxial dislocation. Of the 50 survivors (81.9%), neurologic deficits were present in 15 (30%), and 8 of those had complete spinal cord injuries. The diagnosis of the cervical spine injury was made during the initial evaluation in 56 of the 61 patients (91.8%). Five patients had delayed recognition of their cervical spine injury (2-21 days). The reason for the delay was incomplete CSRs in all patients, despite multiple views (up to 13). The missed injuries occurred in patients in whom complete visualization of the spine was most difficult (i.e., severe degenerative arthritis of the cervical spine in two patients; previous cervical fractures in one patient; instability during resuscitation in one patient). Radiologic misinterpretation occurred in one patient. The diagnosis of cervical spine injury was pursued because of persistent neck pain in two patients, and the development of subtle neurologic findings in three. The neurologic deficits in the three patients resolved.(ABSTRACT TRUNCATED AT 250 WORDS)

Accidents, Traffic↗

PubMed1991

Adaptations to endurance and low velocity resistance training performed in a sequence.

The purpose of this study was to examine the effects of two different sequences of the same two training programs on strength and endurance adaptations. One group completed 5 weeks of low velocity resistance (LVR) training prior to 5 weeks of endurance training (Group SE) while the other group (ES) completed the opposite sequence. Endurance training and resistance training resulted in anticipated increases in aerobic endurance measures and strength, respectively, regardless of the sequence followed. Some maintenance of strength was observed during subsequent endurance training in Group SE. However, the improvements in peak VO2 and submaximal exercise responses that occurred after endurance training in Group ES were not maintained with subsequent LVR training. This investigation suggests that conducting LVR training prior to endurance training may be more beneficial if resistance and endurance training are performed in a sequence.

Adult↗

PubMed1991

Time-motion analysis of and heart rate responses to amateur ice hockey officiating.

The physical activity of referees (n = 4) and linesmen (n = 6) was analyzed from videotapes of four varsity hockey games to determine the frequency, average duration, and total time spent in each of six activity categories. The average duration of activity was low while frequency of occurrence was high. Low intensity activities occupied 96% of total time for referees and 94% of time for linesmen. Heart rate responses were recorded every 5 seconds and synchronized to the videotapes for all referees and 5 linesmen. Heart rates were above 70% of maximum for 70% of the total ice time, which was greater than expected for the observed physical activity. Psychological stress during the course of a varsity hockey game could contribute to the high heart rate responses. It is concluded that training to increase aerobic fitness is an important aspect of ice hockey officiating to increase resistance to fatigue and aid in stress management.

Alberta↗