Long-term parenteral nutrition in unrestrained nonhuman primates: an experimental model

A freely mobile jacket and tether system was developed for the investigation of total parenteral nutrition (TPN)-induced metabolic bone disease and complications of prolonged TPN in 12 Macaca fascicularis nonhuman primates. The animals received TPN for 49 +/- 7 d (means +/- SEM), providing 82 +/- 2 kcal.kg-1.d-1. Serum glucose increased from 3.6 +/- 0.2 mmol/L at baseline to 8.3 +/- 1.9 mmol/L (p less than 0.01) during TPN, and serum albumin decreased from 38 +/- 1 g/L at baseline to 29 +/- 1 g/L (p less than 0.001) during 2.75% amino acid TPN and 30 +/- 2 g/L (p less than 0.01) during 5% amino acid TPN infusion. No significant changes were seen in serum prealbumin, total protein, bilirubin, alanine aminotransferase, and 5'-nucleotidase during TPN infusion. Major complications included catheter sepsis, hyperglycemia, diarrhea, and premature death in six animals. Thus, metabolic complications of prolonged TPN support may be investigated in a freely mobile nonhuman primate.     

Efficacy of calcium glycerophosphate vs conventional mineral salts for total parenteral nutrition in low-birth-weight infants: a randomized clinical trial

To test the efficacy of calcium glycerophosphate (CaGlyP) vs the conventional mineral salts, calcium gluconate plus KH2PO4 + K2HPO4 (CaGluc + P), in promoting mineral retention, 72-h mineral balance, biochemical status, net acid excretion, and growth were assessed in 16 low-birth-weight infants receiving total parenteral nutrition (TPN) containing approximately 1.5 mmol Ca and P.kg-1.d-1 for 5 d. Net retentions of calcium (1.2 +/- 0.2 vs 1.0 +/- 0.2 mmol.kg-1.d-1, means +/- SD) and phosphorus (1.1 +/- 0.3 vs 0.8 +/- 0.3 mmol.kg-1.d-1) from CaGluc + P vs CaGlyP, respectively, were similar, as were retentions of magnesium and sodium, urinary pH, and net acid excretion. Plasma ionized calcium, inorganic phosphorus, alkaline phosphatase, and osteocalcin were normal and not different between groups. CaGlyP is as effective as CaGluc + P in promoting mineral retention and normal mineral homeostasis. However, at intakes of less than or equal to 1.5 mmol Ca and P.kg-1.d-1 from either mineral salt, retention represented only 60% and 45%, respectively, of the predicted intrauterine accretion for calcium and phosphorus. Larger intakes permitted by the more-soluble CaGlyP may be desirable for infants receiving TPN.     

Calcium glycerophosphate as a source of calcium and phosphorus in total parenteral nutrition solutions

Calcium glycerophosphate (CaGP) was tested as an alternative to calcium gluconate (CaGluc) and potassium mono- and dibasic phosphate (KPhos) as a source of Ca and P in total parenteral nutrition (TPN) solutions for piglets. Four-day-old piglets were infused for 7 days with a TPN solution that provided either 4.2 mmol Ca and 2.1 mmol P/kg/24 h as CaGluc and KPhos (the maximum quantities that can be provided using these sources), or 15.0 mmol Ca and 15.0 mmol P/kg/24 h as CaGP. Ca and P retentions were more than six times greater (p less than 0.01) in the piglets receiving CaGP (14.5 +/- 0.2 vs 2.2 +/- 0.3 mmol Ca/kg/24 h and 13.3 +/- 0.4 vs 2.4 +/- 0.1 mmol P/kg/24 h) (Mean +/- SEM). The ratio of Ca to fat-free dry weight, an indicator of bone mineralization, was significantly higher (p less than 0.05) in the humerus (174.8 +/- 2.2 vs 147.2 +/- 6.7) and femur (158.3 +/- 4.8 vs 130.1 +/- 7.8) in the CaGP group. This study showed that CaGP is efficiently used as a source of Ca and P in TPN solutions for piglets. The results suggest that the use of CaGP as the source of Ca and P in TPN solutions may prevent the development of the undermineralized bone seen in low-birth weight infants nourished intravenously.     

The transient hypercholesterolemia of major weight loss

Serum lipoproteins, body composition, and adipose cholesterol contents of six obese women were studied during and after major weight loss by very-low-calorie diets (VLCDs). Subjects started at 168 +/- 11% of ideal body weight, lost 30.3 +/- 3.7 kg in 5-7 mo, followed by 2+ mo in weight maintenance. Serum cholesterol fell from a prediet (baseline) value of 5.49 +/- 0.32 to 3.62 +/- 0.31 mmol/L (P less than 0.01) after 1-2 mo of VLCDs (nadir), after which it rose to 5.95 +/- 0.36 mmol/L (peak, P less than 0.01 compared with nadir and baseline) as weight loss continued. With weight maintenance, serum cholesterol fell to 4.92 +/- 0.34 mmol/L (P less than 0.05 compared with peak). Adipose cholesterol content did not change in peripheral (arm and leg) biopsy sites but rose significantly in abdominal adipose tissue with weight loss. We conclude that major weight loss was associated with a late rise in serum cholesterol, possibly from mobilization of adipose cholesterol stores, which resolved when weight loss ceased.     

Dietary intakes and biochemical markers of selected minerals: comparison of highly trained runners and untrained women

Mineral status of highly trained (HT) women runners (n = 14) and untrained (UT) women (n = 11), as determined from 3-day dietary records, blood, and urine samples, was compared. HT women had significantly higher energy (HT: 2331 +/- 121 vs UT: 1973 +/- 107 kcal/day; p less than 0.05), magnesium (Mg) (HT: 369 +/- 29 vs UT: 262 +/- 18 mg/day, p less than 0.05), and potassium (K) (HT: 3874 +/- 384 vs UT: 2646 +/- 244 mg/day; p less than 0.05) intakes than UT women. However, mean daily intakes of calcium (Ca), iron (Fe), copper (Cu), and sodium (Na) were not different for the two groups. Plasma concentrations and urinary excretion of Ca, Mg, and Cu of HT and UT women did not differ. Plasma Fe concentrations of the two groups were also similar (HT: 21 +/- 2 vs UT: 22 +/- 1 mumol/L), and, although serum ferritin concentrations of HT women were lower than UT women (HT: 18 +/- 4 vs UT: 30 +/- 6 micrograms/L), the difference was not significant. Urinary Na excretion of the two groups did not differ. HT women had a higher K intake than UT women but urinary K excretion of the two groups did not differ. Whether present mineral intakes by HT women are adequate during periods of intensive training remains to be determined.     

Influence of dietary protein on glomerular filtration and urinary albumin excretion in insulin-dependent diabetes.

We investigated the effects of dietary constituents on glomerular filtration (GFR) and albumin excretion rates (AERs) in a cross-sectional study in 39 young subjects with insulin-dependent diabetes. Dietary protein intake correlated significantly in patients with GFRs less than 150 mL/min per 1.73 m2 (r = 0.53, n = 23, P = 0.009), but not with AER. GFR also correlated with mean blood glucose at a concentration less than 12.0 mmol/L (r = 0.61, P = 0.0035). Protein and fat intakes were similar in patients with and without microalbuminuria (AER greater than 20 mg/L) but long-term glycemic control was worse in the former [HbA1 12.4 +/- 2.9% (mean +/- SD) and 10.6 +/- 2.1%, respectively, P = 0.043]. In seven patients, short-term reduction of dietary protein from 2.0 to 1.0 to 0.5 g.kg-1.d-1 produced a progressive fall in GFR by 11.6 +/- 6.0 and 9.6 +/- 5.9 mL/min, respectively (P less than 0.05), but did not consistently affect AER. We conclude that both dietary protein and glycemic control influence GFR but neither alone appears to explain glomerular hyperfiltration. Microalbuminuria was associated with poor glycemic control but not with dietary fat or protein consumption.     

Vitamin E status of patients receiving long-term parenteral nutrition: is vitamin E supplementation adequate?

Vitamin E status of eight patients receiving total parenteral nutrition (TPN), including 10 IU of all-racemic alpha-tocopheryl acetate daily and Intralipid 20% (500 mL; 12 mg of RRR-alpha- and 92 mg of RRR-gamma-tocopherols) two to three times per week for 69 +/- 45 (mean +/- SD) months was assessed by measuring plasma and adipose tissue tocopherol concentrations. Plasma alpha-tocopherols of TPN patients were similar to controls (17.5 +/- 6.6 mumol/L vs 22.4 +/- 5.1), whereas gamma-tocopherols were significantly reduced (6.0 +/- 3.1 vs 11.2 +/- 3.6, p less than 0.03). The adipose tissue alpha- and gamma-tocopherol/triglycerides (TG) were similar (369 +/- 215 nmol/mmol vs 452 +/- 228, and 125 +/- 102 vs 140 +/- 130, respectively), but cholesterol/TG were increased in the TPN patients (7.8 +/- 2.5 mumol/mmol vs 5.1 +/- 3.5, p less than 0.05), suggesting that adipose tissue was relatively TG-depleted and tocopherol/cholesterol measurements better reflect vitamin E status. The mean alpha-tocopherol/cholesterol ratios were significantly lower in the TPN patients than the controls (55 +/- 36 vs 106 +/- 63, p less than 0.04). Thus, current vitamin E supplementation of TPN patients seems insufficient for maintenance of adequate tissue stores.     

Effects of high carnitine supplementation on substrate utilization in low-birth-weight infants receiving total parenteral nutrition

Parenterally fed preterm neonates are known to be at risk for carnitine deficiency. We studied substrate utilization in low-birth-weight infants receiving total parenteral nutrition (TPN) with (A) and without (B) supplementation of 48 mg carnitine.kg-1.d-1 on days 4-7 (birth weights 1334 +/- 282 vs 1318 +/- 248 g, gestational age 32 +/- 2 vs 32 +/- 2 wk, A vs B, respectively). TPN consisted of 11 g glucose.kg-1.d-1 and 2.4 g.kg-1.d-1 of both protein and fat. Plasma carnitine concentrations at day 7 were for free carnitine 11.8 +/- 5.0 vs 164 +/- 56 mumol/L and for acyl carnitine 3.8 +/- 2.0 vs 33.9 +/- 15.4 mumol/L, respectively. Indirect calorimetry at day 7 showed a higher fat oxidation (0.21, -0.31 to +0.60 vs 1.18, 0.70 to 1.95 g. kg-1.d-1, respectively, P less than 0.02, median and interquartile range) in group B and a higher protein oxidation (0.37, 0.30-0.43 vs 0.63, 0.53-0.88 g.kg-1.d-1, P less than 0.001). The time to regain birth weight was also higher in group B (7, 5.5-9 vs 9, 7-14 d, P less than 0.05). Carnitine supplementation and calorie intake were the best explanatory variables for metabolic rate (R2 = 0.45, P less than 0.002). We conclude that carnitine supplementation of TPN in this dosage does not seem advisable.     

Nutritional survey of the US Navy SEAL trainees

The nutritional status of 267 male US Navy Sea, Air, and Land (SEAL) trainees was assessed to determine dietary patterns. Diet records, blood samples, 24-h urine collections, and physical characteristics were analyzed. Energy intake was 3886 +/- 73 kcal/d (SEM) with 15.7 +/- 0.2, 42.9 +/- 0.6, and 41.2 +/- 0.5% of the energy derived from protein, carbohydrate (CHO), and fat, respectively. Mean cholesterol intake (1008 +/- 35.7 mg/d [SEM]) exceeded the US Dietary Goal (less than or equal to 300 mg/d) and serum cholesterol concentration was 5.25 +/- 0.41 mmol/L (SEM). Over 38% of the trainees had cholesterol concentrations greater than 5.3 mmol/L, an indicator of high risk for cardiovascular disease. Mean sodium intake was 250 +/- 22 mmol/d. Over 86% of the trainees consumed greater than 144 mmol/d. Urinary Na excretion was high (146.7 +/- 6.7 mmol/d [SEM]) and correlated with Na intake (r = 0.365; p = 0.001). Potassium and selected vitamin intakes approximated the Military Recommended Dietary Allowances. Fat, cholesterol, and Na intakes were high relative to the dietary goals. Whether more dietary CHO would improve performance in endurance training remains to be determined.     

重复离心对监测碳酸锂药物浓度可靠性研究

目的 针对锂(Li+)盐的治疗剂量(0.4～1.5mmol/L)与中毒剂量(1.6mmol/L)十分接近但又难以避免的状况,探讨样本反复离心后Li+浓度监测的可靠性.方法 选择临床服用碳酸锂治疗达稳态的住院患者,采集血清及肝素钠抗凝血标本,采用离子选择电极直接法分别测定Li+、钾(K+)、钠(Na+)、氯(Cl-)离子浓度,比较对照组和研究组的差异.结果 血清重复离心后K+浓度有升高趋势,但差异无统计学意义(P＞0.05),血浆组K+浓度重复离心后显著升高(P＜0.01),同时血清K+浓度显著高于血浆(P＜0.001);重复离心对血清Na+、Cl-浓度无影响(P＞0.05);虽然血浆Na+、Cl-浓度高于血清(P＜ 0.001),并随离心次数增加显著下降(P＜ 0.001),但无临床实用价值.结论 临床上基于某些无法抗拒的原因所导致的反复离心样本对Li+浓度监测无影响,可以认为是安全和有效的,但为了提高对临床的应答速度而使用肝素抗凝血测定Li+、K+、Na+浓度,应建立新的参考范围.     

Monitoring calcium intake in osteoporosis by assay of nephrogenous cyclic AMP

We studied the relationship between urinary and nephrogenous cyclic adenosine monophosphate (CAMP) and intake of calcium in patients with clinical osteoporosis. Serum and urinary Ca, alkaline phosphatase, and CAMP were measured by standard techniques. Lumbar mineral density was assessed by dual photon absorptiometry. Mean (+/- SD) urinary and nephrogenous CAMP was 4.6 +/- 1.4 mumol/g creatinine (0.52 +/- 0.16 mumol/mmol creatinine) and 15 +/- 8.0 nmol/L GF in patients using an extra gram of Ca carbonate daily and 6.5 +/- 2.6 mumol/g creatinine and 32 +/- 18 nmol/L GF in patients consuming dietary Ca (p less than 0.05). Serum Ca was increased (p less than 0.05) in the supplemented group (9.8 +/- 0.4 vs 9.3 +/- 0.6 mg/dL [2.4 +/- 0.099 vs 2.32 +/- 0.14 mmol/L]) but urinary Ca and serum alkaline phosphatase were similar. Bone mineral density was the same in both (0.88 +/- 0.19 vs 0.87 +/- 0.08 g/cm2). We concluded that CAMP is greater in patients with no supplemental Ca in the diet. This test may be useful to assess patient compliance and biological availability of dietary or supplemental Ca.     

Decreasing dietary sodium while following a self-selected potassium-rich diet reduces blood pressure

Reducing dietary sodium reduces blood pressure (BP), a major risk factor for cardiovascular disease, but few studies have specifically examined the effect on BP of altering dietary sodium in the context of a high potassium diet. This randomized, crossover study compared BP values in volunteer subjects self-selecting food intake and consuming low levels of sodium (Na+; 50 mmol/d) with those consuming high levels of sodium (> or =120 mmol/d), in the context of a diet rich in potassium (K+). Sodium supplementation (NaSp) produced the difference in Na+ intake. Subjects (n = 108; 64 women, 44 men; 16 on antihypertensive therapy) had a mean age of 47.0 +/- 10.1 y. Subjects were given dietary advice to achieve a low sodium (LS) diet with high potassium intake (50 mmol Na+/d, >80 mmol K+/d) and were allocated to NaSp (120 mmol Na+/d) or placebo treatment for 4 wk before crossover. The LS diet decreased urinary Na+ from baseline, 138.7 +/- 5.3 mmol/d to 57.8 +/- 3.8 mmol/d (P < 0.001). The NaSp treatment returned urinary Na+ to baseline levels 142.4 +/- 3.7 mmol/d. Urinary K+ increased from baseline, 78.6 +/- 2.3 to 86.6 +/- 2.1 mmol/d with the LS diet and to 87.1 +/- 2.1 mmol/d with NaSp treatment (P < 0.001). The LS diet reduced home systolic blood pressure (SBP) by 2.5 +/- 0.8 mm Hg (P = 0.004), compared with the NaSp treatment. Hence, reducing Na+ intake from 140 to 60 mmol/d significantly decreased home SBP in subjects dwelling in a community setting who consumed a self-selected K+-rich diet, and this dietary modification could assist in lowering blood pressure in the general population.     

Intravenous vitamins for very-low-birth-weight infants

Term infants and children appear to adapt to large variations in vitamin intakes. This is supported by the finding of similar blood levels of vitamins despite several-fold differences in intake on a body weight basis. By contrast, the finding of marked elevation of some vitamins and low levels of others seen in very-low-birth-weight (VLBW) infants (less than 1500 g) suggest that this group has less adaptive capacity to high- or low-dose intakes. This indicates that their vitamin intakes need to be more closely aligned with actual needs. This paper reviews previously published data on vitamins A, E, B2, and B6 from VLBW infants receiving total parenteral nutrition (TPN). Vitamin A. VLBW infants are relatively deficient in retinol (R) at birth. During TPN large losses of R onto the delivery sets result in a further decline in stores of R as reflected in a progressive decline in plasma R during TPN. Because of the reported lower incidence of bronchopulmonary dysplasia associated with intramuscular vitamin A treatment, alternative methods of vitamin A delivery during TPN have been suggested. First, the vitamins were mixed with Intralipid (IL) and, second, retinyl palmitate (RP) rather than R was used. There was little in vitro loss of R when mixed with IL, and in vivo treatment resulted in higher blood levels after 1 month of retinol administration in IL than seen previously (21.4 +/- 4.2 vs 14.1 +/- 3.7 micrograms/dl).(ABSTRACT TRUNCATED AT 250 WORDS)     

Malnutrition in tubefed nursing home patients with pressure sores.

This study compares the nutritional status and dietary intake of 14 tubefed nursing home patients with pressure sores (age: 70 +/- 5 years, mean +/- SEM) to 12 tubefed patient-controls without sores (age: 60 +/- 7 years). Patients tended to have higher calorie intake (32 +/- 3 kcal/kg) than patient-controls (26 +/- 2 kcal/kg, p = 0.11). Protein intake was significantly higher in patients (1.4 +/- 0.2 g/kg) than patient-controls (0.9 +/- 0.1 g of protein per kg, p less than 0.05). Despite increased calorie and protein intake, biochemical measures of nutritional status were worse in the patients. Serum albumin was lower in patients (33 +/- 1 g/L) than in patient-controls (37 +/- 1 g/L, p less than 0.05) as was level of hemoglobin (patients: 117 +/- 5; patient-controls: 132 +/- 5 g/L, p less than 0.05). Patients with stage IV (severe) sores had lower serum cholesterol levels (3.46 +/- 0.31 mmol/L, n = 5) than patients with stage II/III (milder) sores (4.58 +/- 0.23 mmol/L, n = 9, p less than 0.05). Plasma zinc was low in both patients (11.2 +/- 0.6 mumol/L) and patient-controls (11.5 +/- 0.7 mumol/L, p = NS). Pressure sore surface area was positively correlated with calorie intake per kilogram of body weight (r = +0.59, p less than 0.04) and negatively correlated with body mass index (r = -0.70, p less than 0.03), hemoglobin (r = -0.55, p less than 0.07) and serum cholesterol (r = -0.57, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Failure of additional ketoanalogues of branched chain amino acids to improve the response to parenteral nutrition after experimental trauma in the rat

The ketoanalogues of branched chain amino acids (KAA) may improve the post-traumatic protein metabolism. We studied the effects of additional KAA, supplied as a part of total parenteral nutrition (TPN), on liver protein synthesis and nitrogen balance in rats after standard surgical trauma. A TPN-regimen, containing 36 mmol/kg/day KAA and 58 mmol/kg/day amino acids was compared to an isonitrogenous (1.0 gN/kg/day) TPN-regimen containing 58 mmol/kg/day amino acids and no KAA in a 48 h experiment. The liver protein synthesis measured by perfusion with C14-leucine in vitro was similar in both groups 2 days after surgery (59.2 +/- 16.2 vs. 64.3 +/- 15.6 arbitrary units, mean +/- SD). The nitrogen balances were negative and of similar magnitude (-0.66 +/- 0.36 vs. -0.17 +/- 0.45 gN/kg/48 h, mean +/- SD). We conclude that TPN supplemented by high supply of KAA offers no systematic advantage over TPN alone after experimental surgical trauma.     

Short-chain fatty acids and total parenteral nutrition affect intestinal gene expression

BACKGROUND: The supplementation of total parenteral nutrition (TPN) formulas with short-chain fatty acids (SCFAs) increases glucose uptake and the expression of glucose transporters in parenterally fed animals. Several signals may be involved in intestinal adaptation; however, increased messenger RNA (mRNA) levels for proglucagon and several early-response genes, including c-myc and c-fos, are seen in animals receiving SCFA-supplemented TPN. Although the effects of a mixture of SCFAs are well documented, the relative contribution of individual SCFAs is unknown. Butyrate is a preferred fuel of colonocytes, with documented effects on cellular proliferation and gene expression. Accordingly, this study was undertaken to determine the relative role of butyrate in initiating an adaptive response in nonresected rats receiving TPN. METHODS: Animals received standard TPN for 66 hours, followed by 6 hours of either standard TPN, TPN supplemented with a mixture of SCFAs (acetate, propionate, and butyrate, 60 mmol/L total), or TPN supplemented with butyrate alone (9 mmol/L). An oral control group was fed an elemental diet, similar in macronutrient content to the TPN, so that all animals received the same amount of energy daily. RESULTS: SCFAs increased ileal glucose transporter 2 (GLUT2) mRNA expression compared with the orally fed group. SCFAs also increased proglucagon mRNA expression compared with the TPN group. No changes in Na+K(+)-adenosine triphosphatase or early-response gene expression were found in this study. CONCLUSIONS: In a rat model of TPN, the use of 9 mmol/L butyrate did not have the same effect on GLUT2 and proglucagon expression as a 60-mmol/L mixture of SCFAs. This suggests that the effect of a mixture of SCFAs on intestinal gene expression is not butyrate specific.     

The effect of diet on total antioxidant status, erythrocyte membrane Na+,K+-ATPase and Mg2+-ATPase activities in patients with classical galactosaemia

OBJECTIVE: Classical galactosaemia is characterized by high levels of galactose-1-phosphate (Gal-1-P), galactose and galactitol. In vitro studies have shown modulation of the rat brain Na+,K+-ATPase and Mg2+-ATPase activities by Gal-1-P. The aim of this study was to evaluate the erythrocyte membrane Na+,K+-ATPase and Mg2+-ATPase activities in galactosaemic patients and to correlate them to Gal-1-P, total antioxidant status (TAS) and membrane protein content (PC). PATIENTS AND METHODS: Nine patients (N=9) originally on "loose diet" (group B) were requested to follow their diet strictly (group A). Twelve healthy children were the controls (group C). The activities of the enzymes, TAS and Gal-1-P in blood were determined spectrophotometrically. In the in vitro study, erythrocyte membranes from controls were preincubated with Gal-1-P (300 microM), and then with l-cysteine (0.83 mM) or reduced glutathione (0.83 mM) whereas these from the patients with the antioxidants only. RESULTS: Na+,K+-ATPase, Mg2+-ATPase, TAS and PC were significantly (P<0.001) reduced (0.31+/-0.03, 1.7+/-0.2 micromol Pi/hxmg protein, 0.89+/-0.02 mmol/l, 36.8+/-2.0 g/l, respectively) in group B as compared with those of group A (0.58+/-0.06, 2.5+/-0.2 micromol Pi/hxmg protein, 1.41+/-0.11 mmol/l, 51.5+/-3.1g/l, respectively) and controls (0.67+/-0.05, 3.2+/-0.2 micromol Pi/hxmg protein, 1.65+/-0.12 mmol/l, 64.0+/-3.5 g/l, respectively). Gal-1-P levels in group B was significantly higher than those in group A and controls. Positive correlation coefficients were found between the enzyme activities, PC and TAS whereas Gal-1-P inversely correlated to the enzyme activities. Incubation of the erythrocyte membranes from the patients with the antioxidants failed to restore the activities of inhibited enzymes, whereas the inhibition by Gal-1-P in controls was reversed. CONCLUSIONS: High blood Gal-1-P concentrations resulted in low TAS and PC. The inhibition of Na+,K+-ATPase and Mg2+-ATPase may be due to the presence of free radicals and/or the elevated Gal-1-P.     

Impact of enteral and parenteral nutrition on hepatic and muscle glucose metabolism

Liver and muscle metabolism were assessed in dogs adapted to long-term total parenteral (TPN) and enteral (TEN) nutrition. Studies were done in 13 conscious long-term catheterized dogs in which sampling (artery, portal and hepatic vein, and iliac vein), infusion catheters (inferior vena cava, duodenum), and transonic flow probes (hepatic artery, portal vein, and iliac artery) were implanted. Fourteen days after surgery dogs were grouped to receive TPN or TEN. After 5 days of TPN/TEN, substrate balances across the liver and limb were assessed. The liver was a marked net consumer of glucose in both groups (23.6 +/- 3.3 vs 22.6 +/- 2.8 micromol x kg(-1) x min(-1), TPN vs TEN) despite near normoglycemia (6.5 +/- 0.3 vs 6.7 +/- 0.2 mmol/L). Arterial insulin levels were higher during TEN (96 +/- 6 vs 144 +/- 30 pmol/L; p < .05). The majority (79 +/- 13 vs 76% +/- 7%) of the glucose taken up by the liver was released as lactate. Despite higher insulin levels during TEN the nonsplanchnic tissues consumed a lessor quantity of glucose (25.9 +/- 3.3 vs 16.1 +/- 3.9 micro x mol x kg(-1) x min(-1)). In summary, the liver undergoes a profound adaptation to TPN and TEN making it a major site of glucose uptake and conversion to lactate irrespective of the route of nutrient delivery. However, the insulin requirements are higher with TEN possibly secondary to impaired peripheral glucose removal.     

Effects of a low carbohydrate isoenergetic diet on sleep behavior and pulmonary functions in healthy female adult humans

To study the effects of a low carbohydrate, isoenergetic diet on pulmonary physiology and sleep behavior, we measured pulmonary functions and respiratory gas exchange and carried out ambulatory electroencephalographic studies after a week's intake of isoenergetic diet containing only 50 g carbohydrate per day in 6 healthy female adult humans in a free-living condition. Compared with their normal intake, during the week of low carbohydrate intake there was a rise in the level of fasting plasma 3-hydroxybutyrate from 0.12 +/- 0.07 (mean +/- SD) to 1.01 +/- 0.40 mmol/L(P less than 0.01, paired t-test); a fall in serum bicarbonate from 26.2 +/- 0.75 to 25.0 +/- 1.41 mmol/L (P less than 0.05) and in serum chloride from 107 +/- 1.3 to 105 +/- 1.8 mmol/L (P less than 0.05). Serum urea rose from 4.3 +/- 0.71 to 5.7 +/- 0.70 mmol/L (P less than 0.01), and serum uric acid from 0.34 +/- 0.08 to 0.39 +/- 0.10 mmol/L (P less than 0.05). Functional residual capacity was increased from 2.07 +/- 0.35 to 2.26 +/- 0.34 L (P less than 0.01). Respiratory gas exchange ratio fell from 0.81 +/- 0.05 to 0.75 +/- 0.04 (P less than 0.05) and partial pressure of expired carbon dioxide reduced from 22 +/- 3.3 to 21 +/- 3.1 mmHg (P less than 0.05). There was a reduction in endogenous carbon dioxide production and arterial carbon dioxide tension. An analysis of ambulatory electroencephalogram showed that REM latency increased from 66 +/- 8 to 111 +/- 38 min (P less than 0.05), with no significant changes in sleep time and stages. These studies show that a low carbohydrate isoenergetic diet is tolerable, influences sleep behavior, reduces carbon dioxide production and respiratory gas exchange ratio, and may be therapeutically useful in patients with hypercapnic respiratory failure.     

Trace element intakes of women

1. Energy, protein, zinc, copper, manganese, selenium and dietary fibre intakes of 100 pre-menopausal women (mean age 30.0 +/- 6.1 years) from a university community, and consuming self-selected diets, were calculated using 3 d dietary records and food composition values. Subjects also collected a 24 h food composite during the 3 d record period for analysis of Zn, Cu and Mn by atomic absorption spectrophotometry. Daily analysed intakes were compared with those calculated from the corresponding record day. 2. Mean daily calculated intakes of energy, protein, Zn, Cu, Mn, Se and dietary fibre were 7.54 +/- 1.61 MJ, 74 +/- 18 g protein, 10.1 +/- 3.3 mg Zn, 1.9 +/- 0.6 mg Cu, 3.1 +/- 1.5 mg Mn, 131 +/- 53 micrograms Se, 19.4 +/- 6.6 g dietary fibre. 3. Major food sources for each of the trace elements were (%): Zn meat + substitutes 43, dairy products 23.7; Cu breads and cereals 22, vegetables 21; Mn breads and cereals 47, fruits 12, Se meat + substitutes 38, breads and cereals 30. 4. Highly significant correlations (P = 0.001) were noted for analysed intakes of Zn, Cu and Mn and those calculated from the corresponding record day. Mean calculated intakes were higher (%): Zn 138, Cu 142, Mn 121, than corresponding mean analysed intakes (P = 0.01). However, the mean nutrient densities (mg/MJ) were comparable: Zn analysed 1.2, calculated 1.4; Cu analysed 0.2, calculated 0.2; Mn analysed 0.4, calculated 0.4. 5. All subjects met the Canadian Dietary Standard (CDS) recommended level for Cu but 48% received less than the CDS for Zn, 6% obtaining less than two-thirds of this recommended level. Daily Mn and Se intakes were similar to recent values for North American diets.