PubMed Health⌕ Search

Biomedical subjects

F Greer

Publications and source records attributed to F Greer.

14 recordsLinked to original sources
PubMed2001

Comparison of caloric intake and weight outcomes of an ad lib feeding regimen for preterm infants in two nurseries.

BACKGROUND: Effects on caloric intake and weight gain of an ad libitum (ad lib) feeding regimen for preterm infants may be specific to a special care nursery. OBJECTIVE: To explore across two nurseries the similarity of effect on caloric intake and weight gain of an ad lib feeding regimen compared with a prescribed regimen and the similarity of effect of caloric intake on weight gain. METHODS: All infants participating in the multi-site randomized clinical trial (RCT) of the ad lib feeding regimen were <35 weeks gestational age at birth and had birth weight appropriate for gestational age. Data on caloric intake and weight gain were collected at two nurseries (A, n=22; B, n=78) with the same feeding regimen protocols. Two strategies were used to explore similarity of regimen effect on caloric intake and weight gain. Repeated measures analysis of variance (ANOVA) was used to examine the effect on caloric intake and weight gain of time, feeding regimen, and time-by-regimen interaction for each nursery. RESULTS: In both nurseries, regimen effects were reasonably consistent for caloric intake and weight gain. Caloric intake was lower across nurseries for infants fed ad lib. After accounting for caloric intake, the ad lib regimen did not affect weight gain. The time-by-regimen interaction effect on caloric intake was significant in both nurseries. Caloric intake for infants fed ad lib increased significantly over 5 days. CONCLUSIONS: Despite differences between nurseries in infant characteristics and in protocol implementation, the feeding regimen effect was consistent for caloric intake and weight gain. Further support was found for the development of infant self-regulatory capacity.

Analysis of Variance↗
PubMed2001

Caffeine ingestion decreases glucose disposal during a hyperinsulinemic-euglycemic clamp in sedentary humans.

The purpose of this investigation was to examine the effect of caffeine (an adenosine receptor antagonist) on whole-body insulin-mediated glucose disposal in resting humans. We hypothesized that glucose disposal would be lower after the administration of caffeine compared with placebo. Healthy, lean, sedentary (n = 9) men underwent two trial sessions, one after caffeine administration (5 mg/kg body wt) and one after placebo administration (dextrose) in a double-blind randomized design. Glucose disposal was assessed using a hyperinsulinemic-euglycemic clamp. Before the clamp, there were no differences in circulating levels of methylxanthines, catecholamines, or glucose. Euglycemia was maintained throughout the clamp with no difference in plasma glucose concentrations between trials. The insulin concentrations were also similar in the caffeine and placebo trials. After caffeine administration, glucose disposal was 6.38 +/- 0.76 mg/kg body wt compared with 8.42 +/- 0.63 mg/kg body wt after the placebo trial. This represents a significant (P < 0.05) decrease (24%) in glucose disposal after caffeine ingestion. In addition, carbohydrate storage was 35% lower (P < 0.05) in the caffeine trial than in the placebo trial. Furthermore, even when the difference in glucose disposal was normalized between the trials, there was a 23% difference in the amount of carbohydrate stored after caffeine administration compared with placebo administration. Caffeine ingestion also resulted in higher plasma epinephrine levels than placebo ingestion (P < 0.05). These data support our hypothesis that caffeine ingestion decreases glucose disposal and suggests that adenosine plays a role in regulating glucose disposal in resting humans.

Administration, Oral↗
PubMed2001

Caffeine ingestion elevates plasma insulin response in humans during an oral glucose tolerance test.

We tested the hypothesis that caffeine ingestion results in an exaggerated response in blood glucose and (or) insulin during an oral glucose tolerance test (OGTT). Young, fit adult males (n = 18) underwent 2 OGTT. The subjects ingested caffeine (5 mg/kg) or placebo (double blind) and 1 h later ingested 75 g of dextrose. There were no differences between the fasted levels of serum insulin, C peptide, blood glucose, or lactate and there were no differences within or between trials in these measures prior to the OGTT. Following the OGTT, all of these parameters increased (P < or = 0.05) for the duration of the OGTT. Caffeine ingestion resulted in an increase (P < or = 0.05) in serum fatty acids, glycerol, and plasma epinephrine prior to the OGTT. During the OGTT, these parameters decreased to match those of the placebo trial. In the caffeine trial the serum insulin and C peptide concentrations were significantly greater (P < or = 0.001) than for placebo for the last 90 min of the OGTT and the area under the curve (AUC) for both measures were 60 and 37% greater (P < or = 0.001), respectively. This prolonged, increased elevation in insulin did not result in a lower blood glucose level; in fact, the AUC for blood glucose was 24% greater (P = 0.20) in the caffeine treatment group. The data support our hypothesis that caffeine ingestion results in a greater increase in insulin concentration during an OGTT. This, together with a trend towards a greater rather than a more modest response in blood glucose, suggests that caffeine ingestion may have resulted in insulin resistance.

Administration, Oral↗
PubMed2000

Comparison of caffeine and theophylline ingestion: exercise metabolism and endurance.

This two-part investigation compared the ergogenic and metabolic effects of theophylline and caffeine. Initially (part A), the ergogenic potential of theophylline on endurance exercise was investigated. Eight men cycled at 80% maximum O(2) consumption to exhaustion 90 min after ingesting either placebo (dextrose), caffeine (6 mg/kg; Caff), or theophylline (4.5 mg/kg Theolair; Theo). There was a significant increase in time to exhaustion in both the Caff (41.2+/-4.8 min) and Theo (37.4+/-5.0 min) trials compared with placebo (32.6+/-3.4 min) (P<0.05). In part B, the effects of Theo on muscle metabolism were investigated and compared with Caff. Seven men cycled for 45 min at 70% maximum O(2) consumption (identical treatment protocol as in part A). Neither methylxanthines (MX) affected muscle glycogen utilization (P>0.05). Only Caff increased plasma epinephrine (P<0.05), but both MX increased blood glycerol levels (P<0.05). Muscle cAMP was increased (P<0.05) by both MX at 15 min and remained elevated at 45 min with Theo. This demonstrates that both MX are ergogenic and that this can be independent of muscle glycogen.

Acetyl Coenzyme A↗
PubMed2000

Growth in human milk-Fed very low birth weight infants receiving a new human milk fortifier.

BACKGROUND/AIMS: Human milk fortification has been advocated to enhance premature infants' growth. We, therefore, undertook this study of a new human milk fortifier containing more protein than a reference one. METHODS: Open, randomized, controlled, multiclinic trial, with weekly growth parameters and safety evaluations in premature infants <1,500 g. RESULTS: The 2 groups did not differ in demographic and baseline characteristics. The adjusted daily milk intake was significantly higher in the infants fed reference human milk fortifier (n = 29; 154.2 +/- 2.1 vs. 144.4 +/- 2.5 ml/kg/day, mean +/- SE; p < 0.05). Both human milk fortifiers produced increases over baseline in weight, length, and head circumference, with greater gains observed in the new human milk fortifier-fed infants for the former two parameters (weight gain 26.8 +/- 1.3 and 20.4 +/- 1.2 g/day, p < 0.05; head circumference 1.0 +/- 0.1 and 0.8 +/- 0.1 cm/week; length 0.9 +/- 0.1 and 0.8 +/- 0.1 cm/week, respectively). Serum chemistries were normal and acceptable for age. Study events were typical for premature infants and similar in both groups. CONCLUSIONS: This new human milk fortifier had comparable safety to the reference human milk fortifier and promoted faster weight gain and head circumference growth.

Body Height↗
PubMed1998

Differential effects of serial hemodilution with hydroxyethyl starch, albumin, and 0.9% saline on whole blood coagulation.

STUDY OBJECTIVES: To determine by thrombelastography assessed coagulation, the effects of progressive hemodilution with three intravascular volume expanders. DESIGN: Prospective, controlled, whole blood, volumetric ex vivo hemodilution study. SETTING: University of Pennsylvania Medical Center Operating Rooms. PATIENTS: 60 ASA physical status I and II patients; phlebotomy prior to administration of IV fluids or medications. INTERVENTIONS: Analysis of whole blood clotting determined by six thrombelastographic channels for control and five volumetric hemodilutions (11%, 25%, 33%, 50%, and 75%) with 0.9% saline, 5% albumin, and 6% hydroxyethyl starch (n = 20 for each diluent group). MEASUREMENTS AND MAIN RESULTS: Thrombelastographic parameters R (minutes), angle alpha (degree), MA (mm), and lysis (%) were measured and compared to the sample control for each dilution of the same specimen. There was no significant difference between control groups in any thrombelastographic variable (R, angle alpha, MA, or lysis). No changes were seen in any variable from any diluent at 11% hemodilution. Seventy-five percent hemodilution caused significantly hypocoagulable changes from control for all thrombelastographic parameters for all three diluents. Thrombelastographic indices differed significantly from controls at intermediate hemodilutions. Both colloids caused decreases in measured angle alpha and MA at lower hemodilution than did 0.9% saline. Albumin 5% caused significant hypocoagulable changes from control values at lower hemodilution than did either 0.9% saline or 6% hydroxyethyl starch for all thrombelastographic parameters. Saline 0.9% increased angle alpha significantly at 50% hemodilution. Abnormal lysis did not occur at any dilution. Differing ex vivo effects of three different intravascular fluids thrombelastography assessed coagulation are found. CONCLUSION: No differences were found after 11% hemodilution with any volume expanders. Hemodilution with up to 50% saline maintained thrombelastographic indices. Albumin produced early and profound hypocoagulable effects. Significant hypocoagulability occurred for all three diluents at 75% hemodilution. The study supports the use of albumin in patients at risk for thrombosis, and saline in patients with a need for normal hemostasis.

Albumins↗
PubMed1998

Caffeine, performance, and metabolism during repeated Wingate exercise tests.

Investigations examining the ergogenic and metabolic influence of caffeine during short-term high-intensity exercise are few in number and have produced inconsistent results. This study examined the effects of caffeine on repeated bouts of high-intensity exercise in recreationally active men. Subjects (n = 9) completed four 30-s Wingate (WG) sprints with 4 min of rest between each exercise bout on two separate occasions. One hour before exercise, either placebo (P1; dextrose) or caffeine (Caf; 6 mg/kg) capsules were ingested. Caf ingestion did not have any effect on power output (peak or average) in the first two WG tests and had a negative effect in the latter two exercise bouts. Plasma epinephrine concentration was significantly increased 60 min after Caf ingestion compared with P1; however, this treatment effect disappeared once exercise began. Caf ingestion had no significant effect on blood lactate, O2 consumption, or aerobic contribution at any time during the protocol. After the second Wingate test, plasma NH3 concentration increased significantly from the previous WG test and was significantly higher in the Caf trial compared with P1. These data demonstrate no ergogenic effect of caffeine on power output during repeated bouts of short-term, intense exercise. Furthermore, there was no indication of increased anaerobic metabolism after Caf ingestion with the exception of an increase in NH3 concentration.

Adult↗
PubMed1991

Fast-atom-bombardment mass spectrometry of sulphated oligosaccharides from ovine lutropin.

The positive- and negative-ion f.a.b.-mass spectra and the fragmentation of sulphated oligosaccharides derived from ovine lutropin are described. Negative-ion f.a.b.-m.s. of methylated derivatives offers a sensitive and rapid method for screening glycans for sulphation, for defining the location of sulphated residues, and for sequencing sulphated branches. Positive-ion f.a.b.-m.s. gives complementary data on non-sulphated branches in both complex and hybrid-type sulphated structures.

Animals↗
PubMed1985

Effect of kidney bean (Phaseolus vulgaris) toxin on tissue weight and composition and some metabolic functions of rats.

Inclusion of raw kidney bean (Phaseolus vulgaris) proteins in the diet for rats was shown to affect the weight of some internal organs. Of these, in addition to the well-known hypertrophy of the pancreas attributable to dietary trypsin inhibitors, the observed atrophy of the thymus and the doubling in weight of the small intestine are related to the protein or lectin content of the bean diet, or both. Changes in tissue composition of the small intestine were also recorded. Its protein content increased by about 40-50% and carbohydrate content doubled suggesting the occurrence of increased mucinous glycoprotein secretion. Increased DNA content (by about 30-40%) however also indicated mucosal hyperplasia. Changes were also observed in mineral content, urea concentration and some enzyme activities in sera and urine, possibly as a result of disturbances in systemic metabolism or hormone levels, or both. The results gave further support to previous suggestions that the oral toxicity of kidney-bean lectins involves local reactions in the small intestine in combination with their effects on the systemic immune system and general metabolism.

Animals↗
PubMed1985

Toxicity of kidney bean (Phaseolus vulgaris) in rats: changes in intestinal permeability.

Rats fed on diets containing kidney bean showed increased intestinal permeability to intravenously injected 125I-labelled rat serum proteins after an intragastric challenge with bean proteins. The enhanced accumulation of radioactive serum proteins in the lumen and walls of the small intestine indicated increased vascular permeability. It is suggested that dietary lectins may, at least in part, be responsible for this loss of serum proteins and thus contribute towards the overall toxicity of kidney bean proteins.

Animals↗
PubMed1984

The development of pseudohypoparathyroidism. Involvement of progressively increasing serum parathyroid hormone concentrations, increased 1,25-dihydroxyvitamin D concentrations, and 'migratory' subcutaneous calcifications.

The hormonal changes in the development of pseudohypoparathyroidism ( PSH ) have not, to our knowledge, been previously reported. The male sibling of a child with PSH was studied for 2 1/2 years. At 1 year of age he had generalized subcutaneous calcifications that subsequently migrated over his body. At 3 years of age and over a six-month period, serum calcium levels fell; serum phosphorus, parathyroid hormone (PTH), and 1,25-dihydroxyvitamin D (1,25-[OH]2D) concentrations increased. There was no calcemic, phosphaturic, or urinary cyclic adenosine monophosphate response to PTH. The concentration of serum PTH was suppressed by infusion of calcium and doubled with edetic acid infusion, indicating that the parathyroids were sensitive to changes in calcium levels. Thus, increasing PTH and increased 1,25-(OH)2D concentrations occur in the development of PSH . Migratory skin calcifications may occur. We speculate that increasing the serum PTH level reflects increasing compensatory parathyroid production to overcome a progressive PTH receptor defect and serves, with increased 1,25-(OH)2D concentrations, to prevent severe falls in serum calcium concentrations in the early stage of the disease.

Calcinosis↗
PubMedDate not supplied

The effects of prescribed versus ad libitum feedings and formula caloric density on premature infant dietary intake and weight gain.

BACKGROUND: Although feedings that are organized on an ad lib basis (i.e., in response to infant cues of hunger and of satiation) could enhance an infant's self-regulatory capacities for feeding, ad lib feeding of fully nipple-fed premature infants in a special care nursery has not been examined. OBJECTIVE: To study whether the caloric and protein intake and weight change of fully nipple-fed preterm infants differed by the feeding regimen (prescribed or ad lib) and by the caloric density of the formula (20- or 24-kcalories per ounce). METHOD: The 78 infants who participated in the study were randomized to prescribed or ad lib feeding regimens and, within each regimen, were further randomized to receive either 20-calorie or 24-kcalorie per ounce formula. Dietary intake (volume/kg, caloric intake/kg) and weight change (grams/kg gained or lost) were assessed for each of the 5 study days. Multivariate data analysis was used to examine the effects of feeding regimen and caloric density on dietary intake and weight change, controlling biologic variables (infant gender, race, lung disease diagnosis, treatment with supplemental oxygen, gestational age and weight at birth, and weight on the day prior to full nipple-feeding). RESULTS: Overall, the ad lib feeding regimen had a negative effect on volume intake and caloric intake. Weight gain was influenced by caloric intake, but not by feeding regimen or the caloric density of the diet. With increased full nipple-feeding experience, caloric intake of ad lib feeders approached that of the infants fed on the prescribed regimen. CONCLUSIONS: Development of self-regulatory capacities through ad lib feeding experience was indicated by infant regulation of the volume of intake by the caloric density of the formula, an unexpected finding. Furthermore, the approach of the caloric intake of infants on the ad lib regimen to that of infants on the prescribed regimen suggests they had gained skill in regulating intake with experience. Whether or not the trend for similar intakes would continue beyond 5 days is a question for further study.

Bottle Feeding↗