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Biomedical subjects

J M Erskine

Publications and source records attributed to J M Erskine.

18 recordsLinked to original sources
PubMed2002

Longitudinal investigation of energy expenditure in infants with cystic fibrosis.

OBJECTIVE: To determine when energy expenditure becomes elevated in infants with cystic fibrosis (CF). DESIGN: Longitudinal studies of total energy expenditure (TEE) using doubly labeled water were conducted in infants identified with CF by newborn screening through the first year of life. SETTING: Hospital and community based studies in Denver, Colorado, USA and Cambridge, UK. RESULTS: Eight of the 12 infants enrolled had begun enzyme therapy but were clinically asymptomatic. Four of the 12 infants were heterozygous for the delta F508 mutation, however no difference was seen in TEE from the remaining homozygous infants. TEE was compared to control cohorts at 2, 6 and 12 months of age. There was no difference from the control groups in TEE/kg fat free mass (FFM)/day at 2 months. However, by 6 months of age TEE/kg FFM/day in infants with CF exceeded that of age-matched controls by 25% (P<0.001). This elevation in TEE continued at 12 months of age exceeding that of controls by 30% (P<0.05). CONCLUSIONS: These results indicate that infants with CF have increased energy needs by 6 months of age and that early diagnosis alone does not prevent the development of increased caloric requirements. These findings emphasize the need for close nutritional monitoring to prevent suboptimal growth during infancy in this population. SPONSORSHIP: This research was supported by grant number 5 MO1 RR00069, General Clinical Research Centers Program, National Center for Research Resources, NIH.

Anthropometry↗
PubMed1998

Enteral nutrition for patients with cystic fibrosis: comparison of a semi-elemental and nonelemental formula.

OBJECTIVE: To determine whether differences in tolerance and absorption of fat and nitrogen exist between a semi-elemental nutritional formula without enzyme replacement and a nonelemental formula with enzyme replacement. STUDY DESIGN: Sixteen patients (eight girls and eight boys) with cystic fibrosis, 4 to 20 years of age (12+/-1.3, mean +/- SEM), who were pancreatic insufficient completed two 6-day regimens of nocturnal continuous enteral feedings offered in random order. Forty-four percent of the total daily energy was consumed as enteral tube feedings, and the remaining oral dietary intake remained constant throughout the study. Seventy-two-hour fecal collections from each study period were analyzed for total fat, long-chain fatty acids (LCFAs), medium-chain fatty acids (MCFAs), and nitrogen. RESULTS: Fat absorption was 80.2%+/-2.9% and 82.3%+/-3.1% (p = 0.58) for the semi-elemental and nonelemental formulas, respectively. Similarly, the coefficient of absorption of LCFAs was 69.5%+/-4.5% and 79.6%+/-3.4% (p = 0.30) for the semi-elemental and nonelemental formulas. Malabsorption of MCFAs contributed minimally to total fat malabsorption. There was no difference between formulas for MCFA or for nitrogen absorption, 83.7%+/-1.9% and 87.4%+/-1.4%, p = 0.48. All patients tolerated all feedings, and weight gained was 1.8+/-0.3 kg with no difference in weight gain between the trials. CONCLUSION: A nonelemental formula, with enzyme replacement, is absorbed as well as a predigested formula in patients with CF who are pancreatic insufficient.

Adolescent↗
PubMed1994

Dietary substitution of medium chain triglycerides in subjects with non-insulin-dependent diabetes mellitus in an ambulatory setting: impact on glycemic control and insulin-mediated glucose metabolism.

OBJECTIVE: We have previously shown in an acute inpatient setting that dietary substitution of 77.5% of fat kcal as medium chain triglycerides (MCT) increased insulin-mediated glucose metabolism in patients with non-insulin-dependent diabetes mellitus (NIDDM), and that this effect appeared to be mediated by increases in insulin-mediated glucose disposal. The purpose of this study was to test the application of dietary substitution of medium chain triglycerides as an adjunctive tool in ambulatory therapy of NIDDM. METHODS: Five subjects with NIDDM underwent a baseline 6 hour insulin/glucose euglycemic clamp study, with simultaneous 3H-glucose infusion for calculation of glucose disposal rate and hepatic glucose output. Subjects were then randomized to begin one of two 30-day experimental diets, with long chain (LCT) or medium chain triglycerides (MCT), and subsequent crossover to the other diet. A 6 hour euglycemic clamp was repeated after each diet phase. RESULTS: Diet records and urinary organic acid excretion indicated a high level of dietary compliance by the study participants. Postprandial blood glucose excursions were less after one month on the diet with MCT than after the LCT diet (p = 0.004). However, fasting serum glucose, serum fructosamine (a measure of glycemia), fasting insulin, hepatic glucose output, and insulin-mediated glucose metabolism were not improved by the dietary substitution of MCT. CONCLUSION: These data indicate that supplementation of a tolerable amount of MCT in a conventional diabetic exchange diet has little impact on glycemic control in subjects with NIDDM in an ambulatory setting.

Adult↗
PubMed1994

Macronutrient regulation of lipoprotein lipase is posttranslational.

To examine the relative impact of diet and meal composition on lipoprotein lipase (LPL), high fat (60% of energy) (HF) and high carbohydrate (68%) (HC) diets were fed to Sprague-Dawley rats for 2-3 wk, followed by overnight food deprivation and a meal of the same composition. Heparin-releasable LPL activities, mass and mRNA were measured in heart, diaphragm and soleus muscle and epididymal fat after food deprivation and 1, 2, 4 and 8 h postprandially. No effect of dietary macronutrient composition on LPL activity, protein or mRNA in food-deprived rats was demonstrated. However, in cardiac and diaphragm muscle, heparin-releasable LPL activity was suppressed by HC but stimulated by HF meal-feeding at 4 h. Moreover, in adipose tissue, the HC meal increased LPL activity at 1, 2 and 4 h relative to the basal period. Although there were no consistent effects of meal composition on LPL mass or mRNA in any one tissue, overall LPL mass was generally increased by HC meal-feeding. Because there were meal composition-dependent differences in LPL activity but no detectable differences in mass or mRNA in a particular tissue, LPL regulation by meals seems to be predominantly posttranslational.

Adipose Tissue↗
PubMed1975

In vitro and in vivo interactions between Erwinia amylovora and related saprophytic bacteria.

Under carefully controlled laboratory conditions, a highly virulent strain of Erwinia amylovora coinhabited susceptible host tissues with a yellow saprophytic bacterium, which was invariably isolated from fire blight infected trees, with or without producing symptoms of the disease depending on the status of a number of environmental factors, both climatic and physiological. In particular, variation of temperature and sucrose concentration determined, independently, the equilibrium of a readily reversible alternation of predominance of the two bacteria. It is suggested that E. amylovora may sometimes exist as an avirulent resident on the surface or within healthy host plants when environmental conditions favor growth of the yellow saprophyte rather than the pathogen. Such conditions, which are more likely to be obtained in midsummer and the fall, include temperature fall or rise below or above the optimum for E. amylovora, decreased humidity or diminution of sap flow, and increased sugar content in the host tissues.

Agglutination Tests↗
PubMed1970

Effect of spermine on host-cell lysis and reproduction by a lactic streptococcal bacteriophage.

A method was tested for protecting a Streptococcus lactis strain, ML3, used as a starter in the manufacture of Cheddar cheese, against the lytic activity of its homologous phage, ml(3). At a concentration of 10(-2)m, a naturally occurring polyamine, spermine, in the form of its hydrochloride, protected ML3 against lysis-from-without and lysozyme activity and against lysis by the phage when added at the time of infection or up to 21 min after infection. It was found that the latter protective effect could be accounted for in terms of the spermine preventing the formation of mature particles rather than preventing the escape of viable phage. Single colonies selected from a culture of ML3 cells that had been previously infected with phage ml(3), in the presence of spermine, were all found to have acquired resistance to phage ml(3). They retained this resistance during a 3-month period of daily subculture in broth and, in the absence of spermine, could not be induced to liberate phage or phage components either by the techniques normally used for inducing lysogens or by artificial disruption of the cells. It is concluded that when spermine is added to ML3 cells before a certain critical stage of the phage infection cycle, the process of phage synthesis is irreversibly halted and the cells retain the infecting phage as a defective prophage that confers on the cells immunity to infection by the homologous phage. Phage-resistant cultures did not inherit reduced starter activity in association with their acquired resistance characteristic.

Agar↗
PubMed1970

Effect of chloramphenicol on host-bacteriophage relationships in the lactic streptococci.

Chloramphenicol (CM)-resistant mutants of Streptococcus lactis strain ML3 were obtained either as a consequence of continuous transfer of the bacteria in broth containing increasing amounts of CM or by selecting for high-level resistant derivatives after mutagenic treatment of the bacteria. Some CM-resistant cells obtained by the first method were also resistant to the homologous bacteriophage. Cells trained to grow in the presence of CM developed resistance to some heterologous attacking phages but not to phage ml(3). Mutants selected for phage resistance were not resistant to CM. There appear to be two different loci for CM resistance on the bacterial chromosome: the one for high-level resistance is associated with the phage-resistance locus and the other is independent of it. A concentration of CM (280 mug/ml) that was bacteriostatic for ML3 inhibited the intracellular growth of ml(3) phage in strain ML3-CM(r)I, which had been trained to grow in the presence of that CM concentration, despite the fact that cells of this strain were not phage-resistant per se. The drug had no direct virucidal action and did not prevent adsorption to or penetration of phage into the bacterium. Lysogenization did not occur. It is concluded that the block in phage development probably involves inhibition of synthesis of phage components, either involving deoxyribonucleic acid at an early stage or the phage coat protein at a later one.

Bacteriophages↗