Hourly Blood Samples Research Articles

Arterial Catheter Setup for Glucose Control in Critically Ill Patients: A Randomized Controlled Trial

Use of an arterial catheter to obtain hourly blood samples for intensive insulin therapy monitoring avoids causing patients the discomfort of repeated fingersticks. Returning the clearing volume may decrease procedure-related blood loss by 50% and minimize the risk of anemia. To compare the feasibility of 2 arterial catheter clearing-volume return setups for hourly blood extractions and to evaluate the related complications and the accuracy of arterial samples in determining glycemia. In an open clinical trial, 90 critical patients undergoing intensive insulin therapy who had a radial arterial catheter were randomized to an intervention group-nonwaste needleless setup or nonwaste syringe setup and compared with the standard setup (control group). Mechanical and infectious complications related to the arterial catheter were evaluated. Blood glucose measurements at point-of-care glucometer (arterial catheter or fingerstick sample) were compared with laboratory results (venous blood). No patient had catheter-related infection in the intervention group (an estimated 12776 manipulations); the control group had 2 infection episodes in 5230 catheter-days (an estimated 13 075 manipulations). The incidence of bacterial colonization was not significantly higher in the needleless group than in the syringe group (22.2% vs 12.2%; relative risk, 0.55; 95% CI, 0.16-1.71), with 1778 (SD, 114) and 1918 (SD, 82) catheter manipulations, respectively. Arterial catheter complications were negligible in all patients. Glycemia was detected from arterial catheter samples as effectively as with laboratory results (venous samples) except when hematocrit was less than 25%. Use of blood obtained via an arterial catheter is safe and effective for glucose monitoring in patients undergoing intensive insulin therapy, with no increase in complications of catheterization.

Differential Changes in Hepatic Synthesis of Albumin and Fibrinogen After Severe Hemorrhagic Shock in Pigs

Changes of plasma albumin and fibrinogen after various insults have been described as acute phase responses. This study investigated the acute changes of hepatic synthesis of albumin and fibrinogen after hemorrhage and resuscitation with lactated Ringer's (LR) solution or normal saline (NS) in pigs. Twenty anesthetized pigs were randomized into control (n = 6), LR solution (n = 7), and NS (n = 7) groups. Hemorrhage of 60% estimated blood volume was induced in the LR and NS groups by removing blood from the left femoral artery with a computer-controlled pump, followed by resuscitation with either LR solution at three times the bled volume, or NS to reach the same mean arterial pressure as in the LR group. Stable isotope 1-C-phenylalanine was infused for 6 h with hourly blood sampling and subsequent gas chromatography and mass spectrometry analysis to quantify hepatic protein synthesis. Hemorrhage decreased mean arterial pressure and increased heart rate. Resuscitation with LR solution or NS corrected these changes. Compared with baseline, hemorrhage and resuscitation decreased albumin levels to 49% ± 2% and 44% ± 3% and fibrinogen levels to 50% ± 2% and 53% ± 2% in LR solution and NS (all P < 0.05), respectively. Albumin synthesis was impaired from 8.8 ± 1.4 mg/kg per hour (control) to 5.3 ± 0.8 mg/kg per hour in LR solution and 3.9 ± 0.6 mg/kg per hour in NS (both P < 0.05). No changes were observed in fibrinogen synthesis after hemorrhage and resuscitation with LR solution (4.4 ± 0.7 mg/kg per hour) or NS (3.3 ± 0.4 mg/kg per hour), compared with the control (3.5 ± 0.3mg/kg per hour). Hemorrhage and resuscitation compromised albumin synthesis, but not fibrinogen synthesis. There were no differences in hepatic synthesis of albumin or fibrinogen between LR solution and NS resuscitation.

Insulin secretion, body composition and pig performance are altered by feeding pattern

Three studies investigated the effect of feeding strategy on production performance and endocrine status of growing pigs. For Experiment 1, 20 entire male pigs (70.0 ± 4.6 kg) were allocated randomly to individual pens in one of four climate-controlled rooms. Pigs were fed for 23 days either ad libitum or entrained to feed bi-phasically for two 90-min periods. For Experiment 2, 20 entire male pigs (41.2 ± 3.5 kg) were housed as per Experiment 1. Pigs were fed for 49 days either ad libitum or fed bi-phasically for two 60-min periods. For Experiment 3, 100 female pigs (66.1 ± 3.5 kg) were randomly allocated to individual pens within a commercial piggery and fed for 42 days either ad libitum or bi-phasically for two 60-min periods. Ear vein catheters were inserted into 10 pigs from each group and hourly blood samples were collected for 24 h in Experiments 1 and 2 and for 11 h in Experiment 3. Plasma insulin, non-esterified fatty acid and glucose concentrations were determined in Experiments 1 and 2, and glucose and insulin concentrations in Experiment 3. Feed intake and performance were recorded in all experiments and carcass composition was assessed by computed tomography for Experiment 2. There were no differences in final liveweight between the two treatment groups for all experiments. Pigs fed for two 90-min periods (Experiment 1) showed no difference in feed intake when compared with feeding ad libitum. Pigs in Experiment 2 fed for two 60-min intervals consumed 2.49 kg/pig.day compared with those fed ad libitum that consumed 2.68 kg/day (P = 0.057). In Experiment 3, pigs fed twice daily consumed 2.82 kg/pig.day compared with 2.91 kg/pig.day in ad libitum-fed pigs (P = 0.051). Bi-phasic fed pigs in Experiment 2 had improved (P &lt; 0.05) feed conversion efficiency compared with pigs fed ad libitum. For all experiments, there was no difference in plasma glucose concentrations between the two treatments. In all three experiments, the circulating insulin concentrations for pigs fed ad libitum remained at a constant level throughout the sampling period. However, plasma insulin concentrations for the bi-phasic fed pigs significantly increased ~1 h after both feeding periods during all three experiments. Insulin secretion of pigs fed for two 90-min periods differed from that of pigs fed for two 60-min periods. Plasma insulin concentration increased five-fold following feeding for 60 min, compared with that in pigs fed for 90 min, which increased two-fold. Bi-phasic-fed pigs from Experiment 2 had reduced (P &lt; 0.05) total carcass fat and significantly increased muscle when compared with pigs fed ad libitum. The data showed that feeding pigs at two succinct periods aligned insulin secretion to the time of feeding. Pigs fed for 60 min, unlike those fed for 90-min intervals, had reduced feed intake in comparison to those fed ad libitum. This may suggest that the duration of the feeding bout is important for this response and this may in turn influence both energy balance and the way energy is partitioned.

Role of PGF2α in luteolysis based on inhibition of PGF2α synthesis in the mare

The effects of inhibition of PGF2α synthesis on luteolysis in mares and on the incidence of prolonged luteal activity were studied in controls and in a group treated with flunixin meglumine (FM), a PGF2α inhibitor (n = 6/group). The FM was given every 8 hours (1.0 mg/kg) on each of Days 14.0 to 16.7. Concentration (pg/mL) of PGF2α metabolite averaged over 8 hours of hourly blood sampling at the beginning of each day, was lower in the FM group than in the controls on Day 14 after ovulation (6.7 ± 1.3 vs. 13.8 ± 2.9, P < 0.05), Day 15 (15.0 ± 3.9 vs. 35.2 ± 10.4, P < 0.10), and Day 16 (21.9 ± 5.7 vs. 54.7 ± 11.4, P < 0.03). Concentration (ng/mL) of progesterone (P4) was greater in the FM group than in the controls on Day 14 (10.1 ± 0.9 vs. 7.7 ± 0.9, P < 0.08), Day 15 (9.2 ± 1.0 vs. 4.3 ± 1.0, P < 0.008), and Day 16 (5.6 ± 1.6 vs. 1.2 ± 0.4, P < 0.02). The interval from ovulation to the beginning of a decrease in P4 and to the end of luteolysis (P4 < 1 ng/mL) was each delayed (P < 0.03) by ∼1 day in the FM group. Intervals involving the luteal phase were long (statistical outliers, P < 0.05) in two mares in the FM group, indicating prolonged luteal activity. Results supported the hypotheses that (1) inhibition of PGF2α synthesis interferes with luteolysis in mares and (2) inhibition of PGF2α at the expected time of luteolysis may lead to prolonged luteal activity.

On the relationships between glucocorticoids and feed efficiency in beef cattle

Improvement in the utilization of feed in livestock is an important target of breeding and nutritional programs. Recent evidence indicates a potential association between feed efficiency and fecal cortisol metabolites, which could eventually be used as an indirect assessment of this trait. This evidence is more comprehensively evaluated in here with samples for plasma cortisol (PC; ng/ml) and fecal cortisol metabolites (FCM; ng/ml) collected more often during the entire finishing phase in beef steers. Individual daily feed intake of 112 steers fed a high-moisture corn-based and haylage diet was measured over 168d. Body weight, blood and fecal samples were collected every 14d and ultrasound measures of backfat thickness and longissimus muscle area were taken every 28d. Four productive performance traits were calculated: daily dry matter intake (DMI), average daily gain (ADG), feed to gain ratio (F:G) and residual feed intake (RFI). At the end of the feedlot phase, steers were ranked according to RFI and samples were analyzed for PC and FCM from the 32 steers with greatest and 32 steers with lowest feed efficiency. In addition, a sub-group of 12 steers from each of these two groups with divergent feed efficiency were subjected to hourly blood sampling for 24h. Less efficient steers had greater DMI, F:G and consumed 1.5kg/d more DMI (P<0.05) than steers with improved feed efficiency. No differences (P>0.10) in PC over the 12 biweekly sampling periods between steers with divergent feed efficiency were observed. However, a trend toward significance between 19:00 and 02:00h over the hourly sampling evaluation was noticed, with the sub-group of more feed efficient steers presenting higher levels of PC in this period of the day (P=0.08). On the other hand, FCM levels displayed a distinct pattern between RFI groups over the biweekly sampling period, with more efficient cattle presenting greater levels of these metabolites (P<0.05). This study reinforces the positive association between improved feed efficiency and FCM levels over the finishing phase; and the lack of association between feed efficiency and PC when single samples are collected every two weeks through a single jugular venipuncture performed after handling the cattle for sampling. Further studies to develop sampling protocols for assessing FCM as an indicator trait for feed efficiency are warranted, as well as, studies to understand the role of endogenous glucocorticoids in the performance of the bovine.

Interlinks between sleep and metabolism

Interlinks between sleep and metabolism

Abstract 016: Effect of Dietary Carbohydrate (Amount and Type) on Risk Factors for Cardiovascular Disease and Diabetes: The OmniCarb Trial

Background: Foods that have similar carbohydrate content can differ in the amount they raise blood glucose. The effects of this property, called the glycemic index (GI), on risk factors for cardiovascular disease and diabetes, are not well understood, especially in the context of a healthful dietary pattern that itself improves risk factors. Aims: To study the effects of the amount of dietary carbohydrate (40% vs 58% energy) and GI (40% vs 65% on the glucose scale) on insulin sensitivity (determined by glucose and insulin levels during a 2 hour oral glucose tolerance test), systolic blood pressure (SBP), and fasting lipids (LDL-C, HDL-C, and TG) in non-diabetic, overweight adults with SBP 120 - 159 mmHg. Methods: We randomized 163 adults, mean age 53 y, in a 4 period crossover feeding study. The 4 diets, each studied for 5 weeks, were (1) higher-carbohydrate, higher-GI; (2) higher-carbohydrate, lower-GI; (3) lower-carbohydrate, higher-GI; and (4) lower-carbohydrate, lower-GI. All diets were based on a healthful DASH-type dietary pattern. At the end of each feeding period in a subsample of participants (N=51-57) we obtained hourly blood samples for glucose, insulin, and TG over 12 hours while participants ate the day’s meals in the research facility. Results: The four study diets did not significantly differentially affect insulin sensitivity, LDL-C, or SBP. The lower-carbohydrate or lower-GI diets increased HDL-C by about 4% (with between diet P-values &lt;0.016) and lowered TG by 20% (P&lt;0.031, compared to the higher-carbohydrate, higher-GI diet. Most of these effects were accounted for by lower amount of carbohydrate rather than lower GI. Similarly, the lower carbohydrate or lower GI diets lowered 12-hour blood glucose by an average of 20% (P&lt;0.031) compared to the higher carbohydrate, higher GI diet. The lower-carbohydrate, lower-GI diet reduced 12-hour serum insulin levels the most by 17% (P=0.032). Compared to levels measured when the participants were eating their own diets, all study diets lowered SBP by an average of 9 mm (7%) and LDL-C by 13 mg/dL (9%). Conclusions: In the context of healthful dietary patterns, varying the amount of carbohydrate or its GI in non-diabetic overweight adults does not affect fasting insulin sensitivity, SBP or LDL-C over 5 weeks. HDL-C and triglycerides improved on the lower carbohydrate diets but were not affected by GI. However, postprandial glycemia is reduced either by lowering GI or amount of carbohydrate, and hyperinsulinemia is reduced by the combination of low GI and low carbohydrate. We speculate that consistent associations in populations of reduced CVD event rates with lower intakes of carbohydrate and GI, if causal, result more from reduced postprandial glycemia and hyperinsulinemia than from lower BP and improved lipid risk factors.

Follicular-phase concentrations of progesterone, estradiol-17β, LH, FSH, and a PGF2α metabolite and daily clustering of prolactin pulses, based on hourly blood sampling and hourly detection of ovulation in heifers

Circulating concentrations of hormones were determined each hour in 13 heifers from the end of the luteolytic period to ovulation (follicular phase, 3.5 days). Diameter of the preovulatory follicle was determined every 8 hours, and the time of ovulation was determined hourly. The diameter of the preovulatory follicle decreased 0.8 ± 0.1 mm/h in heifers when there was 1 to 3 hours between the last two diameter measurements before ovulation. The concentration of progesterone (P4) after the end of the luteolytic period (P4 < 1 ng/mL) changed (P < 0.0001), as shown by a continued decrease until Hour −57 (Hour 0 = ovulation), then was maintained at approximately 0.2 ng/mL until 2 hours before the peak of the LH surge at Hour −26, and then a decrease to 0.1 ng/mL along with a decrease in estradiol-17β. Concentrations of LH gradually increased (P < 0.007) and concentrations of FSH gradually decreased (P < 0.0001) after the end of luteolysis until the beginning nadirs of the respective preovulatory surges. A cluster of prolactin (PRL) pulses occurred (P < 0.0001) each day with approximately 24 hours between the maximum value of successive clusters. Hourly concentrations of a PGF2α metabolite decreased (P < 0.007) until Hour −40, but did not differ among hours thereafter. Novel observations included the gradual increase in LH and decrease in FSH until the beginning of the preovulatory surges and follicle diameter decrease a few hours before ovulation. Results supported the following hypotheses: (1) change in the low circulating P4 concentrations during the follicular phase are temporally associated with change in LH concentrations; and (2) PRL pulses occur in a cluster each day during the follicular phase of the estrous cycle.

B27 Disruption of melatonin circadian rhythmicity in Huntington's disease (HD)

<h3>Background</h3> Disruption of the sleep cycle is common in HD. Melatonin regulates sleep in relation to the light/dark cycle, orchestrated by the hypothalamus and suprachiasmatic nucleus. Degeneration in hypothalamic neurons of transgenic mouse models and humans with HD has been reported. One study suggested that the nocturnal rise in melatonin levels is delayed. <h3>Aims</h3> To study the circadian rhythm of melatonin in a 24 h study of control, premanifest and stage II/III HD subjects. <h3>Methods</h3> Control (n=15), premanifest (n=14) and stage II/III (n=13) participants were studied with hourly blood sampling over a standardised 24-h period with identical day/night cycle. Blood samples were taken from an intravenous cannula, immediately centrifuged and stored at −80°C. Melatonin levels were measured by a commercially available radio immuno assay. Estimates of regularity of hormonal pulsatility were undertaken using Fourier transformation. <h3>Results</h3> Individual measures of 24 h melatonin levels showed disturbance in stage II/III HD subjects compared to controls. The main periodicity of pulsatility for melatonin started at 120 min in all groups, but the strength of pulsatility was significantly reduced in moderate and premanifest subjects. This reduction in strength was maintained in stage II/III HD throughout the range of periodicity. <h3>Conclusions</h3> Melatonin circadian rhythms are disrupted in HD and correlate with disease severity providing an explanation for disrupted sleep. Further work is required to understand the underlying mechanism and its potential as an HD biomarker. This study supports melatonin treatment of HD sleep disturbance.

Hormone concentration changes temporally associated with the hour of transition from preluteolysis to luteolysis in mares

The temporal associations of cortisol, estradiol-17β, and oxytocin with pulses of PGFM at the common hour of transition between preluteolysis and luteolysis was studied in plasma from hourly blood samples in mares ( n = 8). The transitional hour was determined from progesterone concentrations and occurred between 2 PM and 2 AM in all mares. Pulses of PGFM were grouped into those occurring at the last pulse of preluteolysis (preluteolytic pulse), at the hour of transition (transitional), and during luteolysis (luteolytic). The preluteolytic PGFM pulse (45 ± 16 pg/ml at peak) and transitional pulse (42 ± 7 pg/ml) are reportedly less prominent than the first luteolytic pulse (193 ± 36 pg/ml). Cortisol increased ( P < 0.05) between −1 h and 0 h (peak) and then decreased ( P < 0.05) within the hours of the luteolytic PGFM pulse but did not change within the preluteolytic and transitional pulses. Estradiol increased ( P < 0.006) during −3 to 2 h of the luteolytic pulse but not for the other pulses. Oxytocin differed for the hours of the transitional PGFM pulse ( P < 0.02) and the luteolytic pulse ( P < 0.03) but did not differ significantly during the hours of the last preluteolytic pulse. Oxytocin increased ( P < 0.05) between −3 h and 0 h and then decreased ( P < 0.05) within each of the transitional and the luteolytic pulses. The oxytocin results are novel and support the hypothesis that on a temporal basis oxytocin in association with PGF2α accounts for the transition between preluteolysis and luteolysis within a single hour in mares, despite the small transitional PGFM pulse.

Pulses of prolactin before, during, and after luteolysis and synchrony with pulses of a metabolite of prostaglandin F2α in heifers

Pulses of prolactin (PRL) and a metabolite of prostaglandin F2α (PGFM) were determined from hourly blood samples collected before, during, and after luteolysis ( n = 7 heifers). Progesterone concentrations were used to partition the results into six 12-h sets from 12 h before to 36 h after luteolysis. Pulses of PRL with a nadir-to-nadir interval of 4.4 ± 0.2 h were detected in each 12-h set. Pulses were rhythmic ( P < 0.05) in six heifers, beginning 12 h before the end of luteolysis. The peak of a PRL pulse was greater ( P < 0.05) for the 12 h after the end of luteolysis than for other 12-h sets, except for the last set of luteolysis. Area under the curve of a pulse was greater ( P < 0.05) for the 24 h that encompassed the end of luteolysis than for two previous 12-h sets. Synchrony between the peaks of PRL and PGFM pulses was greater ( P < 0.03) during and after luteolysis (same hour for 29/39 pairs) than before luteolysis (0/12). Concentration of PRL centralized to the peak (Hour 0) of PGFM pulses was greater ( P < 0.05) at Hours 0 and 1 than at Hours −2, −1, and 3. Results supported the hypothesis that PRL is secreted in pulses in heifers. The pulses were most prominent and rhythmic during the last 12 h of luteolysis and thereafter. The pulse peaks of PRL and PGFM were synchronized for most PRL pulses during and after luteolysis.

Temporal relationships of a pulse of prolactin (PRL) to a pulse of a metabolite of PGF2α in mares

Hourly blood samples were collected from 10 mares during 24 h of each of the preluteolytic, luteolytic, and postluteolytic periods. The autocorrelation function of the R program was used to detect pulse rhythmicity, and the intra-assay CV was used to locate and characterize pulses of prolactin (PRL) and a metabolite of prostaglandin F2α (PGFM). Rhythmicity of PRL and PGFM concentrations was detected in 67% and 89% of mares, respectively. Combined for the three periods (no difference among periods), the PRL pulses were 5.2 ± 0.4 h (mean ± SEM) at the base, 7.5 ± 1.5 h between nadirs of adjacent pulses, and 12.3 ± 1.5 h from peak to peak. The peaks of PRL pulses were greater (P < 0.05) during the luteolytic period (46 ± 14 ng/mL) and postluteolytic period (52 ± 15 ng/mL) than during the preluteolytic period (17 ± 3 ng/mL). Concentrations of PRL during hours of a PGFM pulse were different (P < 0.003) within the luteolytic period and postluteolytic period and were greatest at the PGFM peak; PRL concentrations during a PGFM pulse were not different during the preluteolytic period. The frequency of the peak of PRL and PGFM pulses occurring at the same hour (synchrony) was greater for the luteolytic period (65%, P < 0.01) and postluteolytic period (50%, P < 0.001) than for the preluteolytic period (17%). This is the first report in mares on characterization and rhythmicity of PRL pulses, synchrony between PRL and PGFM pulses, and greater PRL activity during the luteolytic and postluteolytic periods than during the preluteolytic period.

Validity of abbreviated oral fat tolerance tests for assessing postprandial lipemia

Postprandial lipemia is assessed using the oral fat tolerance test (OFTT), a six-hour procedure requiring hourly blood sampling. In order to simplify the test, we investigated whether a)asingle postprandial triacylglycerol concentration, b) an OFTT lasting less than six hours or c) an OFTT requiring fewer blood samples, may accurately assess postprandial lipemia under various conditions. Seventy-two subjects underwent a conventional OFTT. Predictability of single-point concentrations and time-shortened tests was assessed using linear regression and re-sampling analysis. Validity of reduced-sampling tests was assessed using Pearson's correlation coefficients and Bland-Altman analysis. a) A single-point triacylglycerol concentration (3 or 4h postprandially) did not present significant correlation with postprandial lipemia in the hypetriacylglycerolemic, exercise and energy restriction groups (P>0.05), b) Time-shortened OFTT (4h) was able to predict postprandial lipemia in every group studied (R(2)=0.707-0.970, P<0.01), except the hypertriacylglycerolemics (P=0.338), c) Reduced-sampling OFTT (3 or 4 samples) was able to assess postprandial lipemia in every group as well as in the overall sample (r=0.874-0.997, P<0.05). A more convenient, reduced-sampling OFTT may be used alternatively to the conventional OFTT, whereas a time-shortened OFTT may be appropriate only for healthy people.

Circulating hormone concentrations within a pulse of a metabolite of prostaglandin F2α during preluteolysis and early luteolysis in heifers

Plasma from hourly blood samples from two previous studies in heifers was assayed for hormones that were not considered in the previous reports. The objective was to determine the intrapulse temporal relationships between a prostaglandin F2α metabolite (PGFM) pulse and various hormones during preluteolysis and luteolysis. Hormone concentrations were centralized to the peak of a PGFM pulse (Hour 0) and evaluated from Hours −3 to 3. Experiment 1 ( n = 6) was done during early luteolysis. Progesterone decreased during Hours −3 to 0 and then rebounded, but did not return to prepulse concentrations, and concentration of LH increased between Hours −1 and 2. In Experiment 2 ( n = 7), comparisons were made between the last PGFM pulse of preluteolysis and the first pulse of luteolysis. Intrapulse concentrations of LH increased rapidly between Hours 0 and 1 during preluteolysis and gradually between Hours −2 and 2 during luteolysis. Intrapulse differences in cortisol among hours were not significant for preluteolysis and approached significance ( P < 0.06) during luteolysis, owing primarily to an apparent increase between Hours −2 and 1. Oxytocin concentrations showed only an hour effect ( P < 0.0003) from to an increase between Hours −2 and 0 and a decrease between Hours 0 and 2. Results indicated that oxytocin and PGFM concentrations increased and decreased concomitantly and supported the hypothesis that the reported more prominent rebound in progesterone during the descending portion of a PGFM pulse during preluteolysis than during luteolysis involves a greater transient increase in LH.

Sleeping during the day: effects on the 24-h patterns of IGF-binding protein 1, insulin, glucose, cortisol, and growth hormone

Disturbed sleep is a major risk factor for metabolic disturbances, including type 2 diabetes, but the involved mechanisms are still poorly understood. We investigated how an acute shift of sleep to the daytime affected IGF-binding protein 1 (IGFBP1), which is a risk factor for diabetes. Seven healthy men (age, 22-32 years) participated in a night sleep condition (sleep 2300-0700 h) and a day sleep condition (0700-1500 h) with hourly blood samples taken for 25 h (starting at 1900 h) and isocaloric meals every 4th hour awake. The blood samples were analyzed for IGFBP1, insulin, GH, glucose, and cortisol. The acute shift of sleep and meal timing (to 8 h) shifted the 24-h patterns of IGFBP1, glucose, insulin, and GH to a similar degree. However, the day sleep condition also resulted in elevated levels of IGFBP1 (area under curve (AUC)+22%, P<0.05), and reduced glucose levels (AUC-7%, P<0.05) compared with nocturnal sleep. Sleeping during the day resulted in elevated cortisol levels during early sleep and reduced levels in late sleep, but also in increased levels the subsequent evening (P's<0.05). Sleep-fasting seems to be the primary cause for the elevation of IGFBP1, irrespective of sleep timing. However, sleeping during the day resulted in higher levels of IGFBP1 than nocturnal sleep, suggesting altered metabolism among healthy individuals, which may have implications for other groups with altered sleep/eating habits such as shift workers. Moreover, sleep and meal times should be accounted for while interpreting IGFBP1 samples.

Daylong pituitary hormones in morbid obesity: effects of bariatric surgery

Moderate obesity is known to be associated with multiple endocrine abnormalities. Less information is available on the hormonal status of patients with morbid obesity and on the effects of major weight loss. We studied 16 severely obese (BMI 40.6-69.9 kg/m(2)) nondiabetic patients and 7 nonobese (BMI range 24.6-27.7 kg/m(2)), sex- and age-matched healthy volunteers. During 24 h in a metabolic ward, four meals were administered and hourly blood samples were drawn from a central venous catheter for the measurement of glucose, insulin, leptin, thyrotropic hormone (TSH), growth hormone (GH) and prolactin. Insulin sensitivity was measured by a euglycaemic hyperinsulinaemic clamp. Studies were repeated 6 months after biliopancreatic diversion, a mainly malabsorptive surgical approach, which caused an average weight loss of 35+/-4 kg (or 26+/-2% of initial weight). Compared with controls, patients were hyperinsulinaemic (290+/-31 vs 88+/-4 pmol l(-1), P=0.0002), insulin resistant (23.5+/-2.8 vs 52.9+/-4.9 micromol min(-1) kg(FFM)(-1), P=0.0006) and hyperleptinaemic (52.5+/-5.8 vs 10.9+/-3 ng ml(-1), P=0.0002). Plasma TSH levels were increased throughout the day-night cycle (averaging 2.02+/-0.18 vs 1.09+/-0.19 muU ml(-1) of controls, P=0.01), whereas serum GH levels were suppressed (0.46+/-0.10 vs 3.01+/-1.15, P=0.002). Following surgery, the hyperinsulinaemia and insulin resistance were fully normalized; in concomitance with a major drop in leptin levels (to 14.4+/-2.7 ng ml(-1), P=0.02), TSH decreased and GH increased to near-normal levels. In the whole dataset, mean 24-h leptin levels were directly related to mean 24-h TSH levels after controlling for confounders this relationship was lost only after adjusting for fat mass. We conclude that in morbid obesity leptin is a determinant of changes in pituitary function.

Meal‐related Changes in Ghrelin, Peptide YY, and Appetite in Normal Weight and Overweight Children

Ghrelin and peptide YY (PYY) are two gut hormones that have effects on appetite. Our objectives were to characterize the patterns of secretion of these hormones in response to feeding in school-age children and determine whether there were differences between normal weight (NW) and overweight (OW) subjects. This was a cross-sectional study at one tertiary care center. Subjects were 7- to 11-year-old healthy NW and OW volunteers recruited from local advertisements. Following an overnight fast, the subjects were given a standardized breakfast and lunch and had nine hourly blood samples for total ghrelin and total PYY. We assessed whether ghrelin and PYY levels changed from the preprandial to postprandial state and corresponded to reported hunger/satiety. Hunger ratings were similar between the two groups throughout the study period. Ghrelin was not suppressed after eating, did not rise prior to the next meal, and did not correspond to hunger ratings in either group. PYY increased postprandially and decreased preprandially in the NW group, but OW children exhibited this pattern for only part of the day. PYY levels incompletely corresponded to reported satiety in the OW group. Mixed meal consumption had little effect on ghrelin secretion and a variable effect on PYY secretion in young children in our study. Differences that were observed between the groups do not suggest that an abnormality in their secretion contributes to the development of obesity.

Effect of Prior Exercise on Postprandial Triglycerides in Overweight Young Women after Ingesting a High-Carbohydrate Meal

To examine the effect of prior exercise on the postprandial lipid response to a high-carbohydrate meal in normal-weight (NW=BMI <25) and overweight (OW=BMI >or= 25) women (age 18-25), 10 NW and 10 OW participants completed 2 conditions separated by 1 month. In the morning, the day after control (CT=no exercise) or exercise conditions (EX=60 min cycling at 60% VO(2peak)), participants consumed a high-carbohydrate meal (80% CHO, 15% protein, 5% fat; 75 kJ/kg BM) followed by 6 hr of hourly blood sampling. Blood was analyzed for triglycerides (TG), blood glucose (BG), and insulin (IN). TG levels over the 6-hr period were lower in NW than OW (p= .021) and lower in EX than in CT (p= .006). Area under the curve (AUC) for TG was lower in NW than OW (p= .016) and EX than CT (p= .003). There were nonsignificant tendencies for reduced BG over time (p= .053) and AUC (p= .083), and IN AUC was lower in EX than in CT (p= .040) for both groups and lower in NW than in OW (p= .039). Prior exercise improved TG levels after a high-carbohydrate meal in both groups, and OW women demonstrated a greater postprandial lipemic response than NW regardless of condition. There were tendencies for improved glucose removal with prior exercise in NW vs. OW. Acute exercise can improve postprandial TG responses and might also improve postprandial BG and IN after a large meal in NW and OW young women.

Thiazolidinediones and the renal and hormonal response to water immersion-induced volume expansion in type 2 diabetes mellitus

Thiazolidinediones cause sodium retention and edema by a direct effect on the kidneys. The aim of this study was to use the technique of head-out water immersion to investigate the effects of rosiglitazone on sodium and volume homeostasis in subjects with type 2 diabetes mellitus. The volume expansion response to water immersion was compared with the response on a non-immersion control day in 12 nondiabetic male subjects and 8 diet-controlled male type 2 diabetic subjects with hourly blood and urine sampling over a 4-h period. This was repeated after both groups had taken 4 mg of rosiglitazone daily for 7 days. Immersion produced a natriuresis in both groups (P < 0.001). An impairment of this natriuresis was seen in the diabetic subjects (P = 0.006). However, when rosiglitazone was taken, there was no significant difference in immersion-induced natriuresis compared with nondiabetic controls (P = 0.2). There was an immersion-induced rise in atrial natriuretic peptide (ANP) and urinary cyclic guanosine monophosphate (cGMP), in the healthy subjects (ANP P = 0.001, cGMP P = 0.043), which was not seen in the diabetic subjects (ANP P = 0.51, cGMP P = 0.74). Rosiglitazone restored the immersion-induced increase in cGMP excretion and rise of ANP in the diabetic group (ANP P = 0.048, cGMP P = 0.009). This study confirms that type 2 diabetic subjects have an impaired natriuretic response to acute volume expansion, which appears to be enhanced rather than diminished by rosiglitazone. This may be related to its effects in increasing natriuretic peptides and restoring the impaired cGMP excretion to volume expansion.

Effects of Exercise Timing on Lipoprotein Remodeling during the Postprandial Period

PURPOSE: We examined whether an acute exercise bout performed 4 or 16 hours prior to a high fat meal affected postprandial lipemia and lipoprotein metabolism. METHODS: Twelve normolipidemic, normally-active men performed three oral fat tolerance tests (OFTT) in random order: exercise 16h prior to the OFTT (EX-16), exercise 4h prior to the OFTT (EX-4), and no exercise (NE). Dietary intake and exercise were tightly controlled 5 days prior to each OFTT. The exercise session included a combination of whole body resistance exercise (3 sets of 10 repetitions of 5 exercises) and treadmill running (30min). After a baseline fasting blood sample, subjects consumed the high fat meal (13kcal/kg and 1.4g fat/kg body weight) followed by hourly blood samples for 6h. RESULTS: There were no significant differences between trials for dietary intake, perceived rate of exertion, or muscle soreness demonstrating successful replication of trials. Exercise attenuated the triacyglycerol total area under the curve by 26% and 16% in EX-16 and EX-4, respectively, with no significant differences between exercise trials. ApoC-III, VLDL-C, and LDL size significantly decreased during the PP period. EX-16 had a significantly lower response than the other two trials in VLDL-C and ApoE. There were no significant changes in CETP activity or HDL-C. LCAT activity was significantly elevated at 2h in the EX-4 trial (mean ± SD; 25.6 ± 8.7g/mL/h) compared to EX-16 (19.9 ± 7.1g/mL/h) or NE (18.4 ± 8. 1g/mL/h). CONCLUSIONS: Exercise performed either 4 or 16 hours prior to a meal decreased the lipemic response, but failed to prevent the reduction in LDL particle size during the postprandial period.