Response of growing pigs to the inclusion of hybrid rye in low or high-energy diets

Previous research has shown reduced feed intake and growth rate in pigs fed diets with hybrid rye replacing wheat. A reduction in growth rate caused by reduced feed intake will conceivably be counteracted by increasing the dietary energy level. Our objective, therefore, was to determine the effects of 40% hybrid rye inclusion replacing wheat in diets formulated to be either low or high net energy (NE) on growth, feed intake, energy digestibility, and lesion scores in growing-finishing pigs. We hypothesized that pigs fed 40% hybrid rye would perform better on the high than the low energy diets. A total of 160 pigs (body weight [BW] 70.1 kg) housed in 32 pens, 5 pigs per pen, were fed diets with 0% or 40% hybrid rye (var. 'KWS Bono'; KWS LOCHOW GMBH), either with low (2,350) or high (2,450) kcal NE per kg of diet over two growth phases (phase 1; 70 to 85 kg BW; phase 2; 85 to 130 kg BW). The BW, and feed disappearance were measured on days 0, 8, 17, 28, 42, and 50. Fecal samples obtained in phase 2 (~100 kg BW) were used to calculate apparent total tract digestibility (ATTD) of gross energy (GE). Lesion scores were measured weekly. The ATTD of GE was unaffected by rye inclusion and was reduced in low vs. high NE diets. Overall, (days 0 to 50), pigs fed the low-energy rye diet gained 0.08 kg/d less (P < 0.01) than those fed the high-energy rye diet or the low-energy diet without rye, which was caused by a reduced weight gain during the initial 17 d of the trial. Final BW and overall feed intake were not affected by rye inclusion or NE level. The NE intake was greater (P < 0.05) and feed efficiency (G:F) was reduced (P < 0.05) in pigs fed rye diets compared to those fed diets without rye, whereas there was no effect of NE level on NE intake or G:F. There was no effect of rye inclusion or NE level on lesion scores. In conclusion, pigs can be fed diets including 40% hybrid rye with only minor changes in growth performance. Increasing the NE level of the first phase diet in the grower-finisher barn may be useful to avoid a reduction in growth performance when feeding hybrid rye.

In vitro addition of epinephrine, norepinephrine, and carnitine alters palmitate oxidation and esterification in isolated ovine hepatocytes

Hepatocytes from 4 wethers were used to study the effects of carnitine and increasing concentrations of epinephrine and norepinephrine on palmitate oxidation and esterification. Liver cells were isolated from the wethers and incubated in Krebs-Ringer bicarbonate buffer with 1 mM [¹⁴C]-palmitate. Radiolabel incorporation was measured in CO₂, acid-soluble products, and esterified products, including triglyceride, diglyceride, and cholesterol esters. Carnitine increased production of CO₂ and acid-soluble products from palmitate by 41% and 216%, respectively, but had no effect on conversion of palmitate to esterified products. Epinephrine had a quadratic-increasing effect on palmitate oxidation to CO₂, but norepinephrine did not increase palmitate oxidation to CO₂. Neither epinephrine nor norepinephrine affected the production of acid-soluble products from palmitate. Increasing concentrations of norepinephrine and epinephrine linearly increased rates of triglyceride formation from palmitate. Increasing norepinephrine concentrations linearly increased diglyceride and cholesterol ester formation from palmitate in the presence of carnitine; epinephrine did not affect diglyceride or cholesterol ester formation. In general, catecholamine treatment had the greatest effect on the formation of esterified products from palmitate, and effects of norepinephrine were more pronounced than epinephrine. Conditions that result in catecholamine release might lead to fat accumulation in liver.

Greenhouse gases and performance of growing pigs fed wheat-based diets containing wheat millrun and a multi-carbohydrase enzyme

The objective of this project was to determine the impact of feeding growing pigs with high wheat millrun diets supplemented with a multi-carbohydrase enzyme (amylase, cellulase, glucanase, xylanase, and invertase activities) on nutrient digestibility, growth performance, and greenhouse gas (GHG) output (carbon dioxide, CO2; nitrous oxide, N2O; methane, CH4). Three experiments were conducted utilizing six treatments arranged as a 3 × 2 factorial (0%, 15%, or 30% wheat millrun; with or without enzyme) for the digestibility experiment or as a 2 × 2 factorial (0% or 30% wheat millrun; with or without enzyme) for the performance and GHG experiments. The digestibility, performance, and GHG experiments utilized 48 individually housed pigs, 180 pigs housed 5 per pen, or 96 pigs housed 6 per chamber, respectively. Increasing wheat millrun up to 30% in the diet of growing pigs resulted in decreased energy, nitrogen (N) and phosphorus (P) apparent total tract digestibility and net energy content (P < 0.01). Overall, average daily gain (ADG) and gain to feed ratio were reduced in pigs fed wheat millrun (P < 0.05). Enzyme supplementation had minimal effects on the digestibility or performance parameters measured. Feeding diets with 30% millrun did not affect GHG output (CH4: 4.7 and 4.9; N2O: 0.45 and 0.42; CO2: 1,610 and 1,711 mg/s without or with millrun inclusion, respectively; P > 0.78). Enzyme supplementation had no effect on GHG emissions (CH4: 4.5 and 5.1; N2O: 0.46 and 0.42; CO2: 1,808 and 1,513 mg/s without or with enzymes, respectively; P > 0.51). Overall, the carbohydrase enzyme had minimal effects on parameters measured, regardless of wheat millrun inclusion (P > 0.10). Although energy, N and P digestibility, and ADG were reduced, the inclusion of up to 30% wheat millrun in the diet has no effect on GHG emissions from growing pigs (P > 0.10).

Effects of in vivo phlorizin treatment and in vitro addition of carnitine, propionate, acetate, and 5-tetradecyloxy-2-furoic acid on palmitate metabolism in ovine hepatocytes

Modulatory effects of l-carnitine, acetate, propionate, and 5-tetradecyloxy-2-furoic acid (TOFA; an inhibitor of acetyl-CoA carboxylase) on oxidation and esterification of [1-¹⁴C]-palmitate were studied in hepatocytes isolated from phlorizin-treated and control wethers. Our hypotheses were that (1) palmitate oxidation would be greater in hepatocytes from sheep injected with phlorizin; (2) l-carnitine would increase palmitate oxidation more in hepatocytes from sheep injected with phlorizin; and (3) acetate and propionate would decrease oxidation in sheep hepatocytes partly through action of acetyl-CoA carboxylase. Palmitate metabolism did not differ between cells from control and those from phlorizin-treated wethers. Carnitine increased oxidation of palmitate to CO₂ and acid-soluble products (ASP; mainly ketone bodies) and decreased esterification of palmitate in isolated hepatocytes from both groups of wethers, but the increase in oxidation to ASP was greater in cells from phlorizin-treated wethers. Propionate increased palmitate oxidation to CO₂ in phlorizin-treated wethers. Propionate increased oxidation of palmitate to ASP in control wethers but decreased oxidation to ASP in phlorizin-treated wethers. Propionate increased esterification of palmitate to total esterified products and triglyceride, and the effect was larger in phlorizin-treated wethers. Acetate decreased palmitate esterification to total esterified products in control wethers, but the effect was blunted in phlorizin-treated wethers. Acetate did not affect palmitate oxidation. Addition of TOFA increased production of triglyceride from palmitate in the presence of propionate. The lack of interaction between TOFA and propionate indicates that propionate does not inhibit carnitine palmitoyltransferase I via cytosolic generation of methylmalonyl-CoA by acetyl-CoA carboxylase. In conclusion, although in vivo phlorizin treatment did not affect in vitro metabolism of palmitate by isolated ovine hepatocytes, phlorizin increased the stimulatory effect of carnitine on oxidation of palmitate to ASP and the inhibitory effect of propionate on oxidation of palmitate to ASP. Metabolism of acetate and propionate by acetyl-CoA carboxylase did not affect palmitate oxidation or esterification. Results provide additional insight into control of fatty acid metabolism in hepatocytes.

Effects of supplementing processed straw during late gestation on sow physiology, lactation feed intake, and offspring body weight and carcass quality1

This study investigated the effects of supplementing late gestation sow diets with processed or unprocessed oat or wheat straw on physiology, early lactation feed intake, and offspring performance. One hundred fifty gestating sows were randomly assigned to 1 of 5 dietary treatments (30 sows per diet) from day 86 of gestation until farrowing. Treatments, arranged as a 2 × 2 factorial plus a control, were a standard gestation diet (control) or control supplemented with 10% wheat or oat straw, processed or unprocessed. Sows were fed a standard lactation diet postfarrowing. The processed straws were produced by high-pressure compaction at 80 °C. On day 101 of gestation (day 15 of the trial), blood samples were collected from a subset of sows (n = 8 per treatment) through ear vein catheters and analyzed for insulin, insulin-like growth factor 1 (IGF-1), prolactin, glucose, and urea concentrations. Fecal samples were collected on days 103 to 104 of gestation to determine nutrient digestibility, and feeding motivation was investigated on day 104. Litter characteristics and sow feed intake were recorded for 7 d postfarrowing. Three piglets per litter were selected at weaning, fed standard diets, and followed to market. Treatment had no effect on feeding motivation, piglet characteristics at birth, estimated milk production, and offspring BW at market or carcass quality. Processed straw improved DM digestibility and energy content and the effect was greater with oat straw (straw × processing effect, P < 0.05). Pre- and postprandial glucose concentrations tended to decrease (P < 0.10) with processing of wheat, but not oat straw, and this effect was more apparent in the preprandial samples. Preprandial prolactin concentration increased with oat but decreased with wheat straw, whereas postprandial IGF-1 and prolactin concentration increased with processing of wheat, but not oat straw (straw × processing, P < 0.05). Sow lactation feed intake improved (P < 0.05) with oat straw supplementation relative to wheat straw. Piglet weaning weight increased (P < 0.05) with oat straw supplementation and processing improved (P < 0.05) nursery exit BW. However, straw supplementation, regardless of processing, had no effect on offspring BW at market or carcass quality. Overall, oat straw supplementation had a greater impact on sow physiology and provided benefits for sows in late gestation, and there was some indication that further benefits could be obtained through mild processing.

Body fat mobilization during lactation in high-producing sows fed varied omega-6 to omega-3 fatty acid ratios

The effects of reducing dietary omega (n)-6 to n-3 fatty acid (FA) ratios on body fat mobilization in lactating sows (n = 100) were investigated. Treatments consisted of a control (tallow, low polyunsaturated FA, 8:1 n-6:n-3 ratio), 3 diets with plant oil based ratios (9:1P, 5:1P, and 1:1P), and a 5:1 fish oil diet (5:1F). An epinephrine [1.6 μg kg−1 body weight (BW)] challenge was used to measure adipose tissue lipolytic activity (glycerol, NEFA, and leptin) on d 5 of lactation from a subset of sows (9:1P and 1:1P groups) fitted with jugular catheters. Lactation feed intake was greatest for control and 5:1P-fed sows (8.3 kg d−1), lowest for 1:1P-fed sows (7.4 kg d−1), and intermediate for 9:1P- and 5:1F-fed sows (7.7 kg d−1; P = 0.047). Piglet average daily gain (ADG) and estimated milk output were unaffected by diet (P > 0.10). The 1:1P-fed sows had (P < 0.10) greater backfat thickness, increased circulating leptin, and reduced feed intake, which are correlated (P < 0.10) with increased circulating glycerol and NEFA. Sows fed a plant oil based 1:1 n-6:n-3 FA ratio appeared to be in a state of negative energy balance; however, as no effects were observed on piglet ADG, these sows were able to provide the same level of nutrients to their offspring as the 9:1P fed sows.

Changing the omega-6 to omega-3 fatty acid ratio in sow diets alters serum, colostrum, and milk fatty acid profiles, but has minimal impact on reproductive performance

This experiment tested the hypothesis that reducing the omega-6 (n-6) to omega-3 (n-3) fatty acid (FA) ratio in sow diets will improve performance, characterized by increased litter size, decreased preweaning mortality, and improved growth performance. Second, we determined if the FA profile in sow and piglet blood, colostrum, and milk are altered when sows are fed diets with varied n-6:n-3 ratios and if the dietary FA ratio impacts circulating concentrations of IgG, IgA, eicosapentaenoic (EPA), or docosahexaenoic (DHA) acid. Sows (n=150) were assigned to 1 of 5 treatments (each divided into gestation and lactation diets) on d 80 of gestation. Period 1 (P1) is defined as d 80 of gestation to weaning and Period 2 (P2) refers to the subsequent breeding to weaning. Diets were wheat and barley based (5% crude fat) and treatments consisted of a control (tallow), 3 diets with plant oil-based n-6:n-3 ratios (9:1P, 5:1P, and 1:1P), and a 5:1 fish oil diet (5:1F). Litter size was unaffected by treatment during P1 and P2 (P>0.10). In P1, birth weight was unaffected by diet (P>0.10); however, weaning weight (P=0.019) and ADG from birth to weaning (P=0.011) were greatest for piglets born to 9:1P and 5:1P sows. During P2, 5:1F sows consumed 10% less feed during lactation (P=0.036), tended to have reduced piglet birth weights (P=0.052), and piglet weaning weight was reduced by 0.8 kg (P=0.040) relative to the other diets. Colostrum and piglet serum IgA and IgG concentrations were unaffected by diet (P>0.10). Serum n-3 FA were greatest in sows (P<0.01) consuming 1:1P and 5:1F diets and in their offspring (P=0.014). Serum α-linolenic acid (ALA) was greatest in 1:1P sows and EPA and DHA were greatest in 5:1F sows (P<0.01). In pre-suckle piglet serum, ALA did not differ among treatment groups (P>0.10). Relative to piglets of sows consuming the control diet, EPA was 2.5-fold greater in the 1:1P group and 4-fold greater in 5:1F group (P<0.01) before suckling. In post-suckle samples, ALA was greatest in piglets from the 1:1P sows (P<0.01) and EPA and DHA were greatest in piglets from the 5:1F sows (P<0.01). Feeding diets with plant-based n-6:n-3 ratios of 5:1 or 1:1 did not impact performance relative to a control group but improved the conversion of ALA into EPA and increased the transfer of n-3 to piglets through milk. When a fish-based 5:1 ratio diet was fed, pre-weaning mortality was increased, and piglet birth and weaning weights decreased.

Effects of dietary soybean oil on pig growth performance, retention of protein, lipids, and energy, and the net energy of corn in diets fed to growing or finishing pigs

The objectives of this experiment were 1) to determine if dietary soybean oil (SBO) affects the NE of corn when fed to growing or finishing pigs, 2) to determine if possible effects of dietary SBO on the NE of corn differ between growing and finishing pigs, and 3) to determine effects of SBO on pig growth performance and retention of energy, protein, and lipids. Forty-eight growing (initial BW: 27.3 ± 2.5 kg) and 48 finishing (initial BW: 86.0 ± 3.0 kg) barrows were used, and within each stage of growth, pigs were allotted to 1 of 6 groups. Two groups at each stage of growth served as an initial slaughter group. The remaining 4 groups were randomly assigned to 4 dietary treatments and pigs in these groups were harvested at the conclusion of the experiment. A low-lipid basal diet containing corn, soybean meal, and no added SBO and a high-lipid basal diet containing corn, soybean meal, and 8% SBO were formulated at each stage of growth. Two additional diets at each stage of growth were formulated by mixing 25% corn and 75% of the low-lipid basal diet or 25% corn and 75% of the high-lipid basal diet. Results indicated that addition of SBO had no effects on growth performance, carcass composition, or retention of energy, protein, and lipids but increased (P < 0.05) apparent total tract digestibility of acid hydrolyzed ether extract and GE. Addition of SBO also increased (P < 0.05) DE and NE of diets, but had no effect on the DE and NE of corn. Finishing pigs had greater (P < 0.05) growth performance and retention of energy, protein, and lipids than growing pigs. A greater (P < 0.05) DE and NE of diets was observed for finishing pigs than for growing pigs and the DE and NE of corn was also greater (P < 0.05) for finishing pigs than for growing pigs. In conclusion, addition of SBO increases the DE and NE of diets but has no impact on the DE and NE of corn. Diets fed to finishing pigs have greater DE and NE values than diets fed to growing pigs and the DE and NE of corn are greater for finishing pigs than for growing pigs.

Effects of dietary soybean hulls and wheat middlings on body composition, nutrient and energy retention, and the net energy of diets and ingredients fed to growing and finishing pigs

The objectives of this experiment were 1) to determine the effect of dietary soybean hulls (SBH) and wheat middlings (WM) on body composition, nutrient and energy retention, and the NE of diets and ingredients fed to growing or finishing pigs and 2) to determine if finishing pigs use the energy in SBH and WM more efficiently than growing pigs. Forty growing barrows (initial BW: 25.4 ± 0.7 kg) and 40 finishing barrows (initial BW: 84.8 ± 0.9 kg) were randomly allotted to 5 groups within each stage of growth. Two groups at each stage of growth served as the initial slaughter group. The remaining pigs were randomly assigned to 3 dietary treatments and harvested at the conclusion of the experiment. The basal diet was based on corn and soybean meal and was formulated to be adequate in all nutrients. Two additional diets were formulated by mixing 70% of the basal diet and 30% SBH or 30% WM. In the growing phase, ADG, G:F, and retention of lipids were greater (P < 0.05) for pigs fed the basal diet than for pigs fed the diets containing SBH or WM. Retention of energy was also greater (P < 0.05) for pigs fed the basal diet than for pigs fed the SBH. In the finishing phase, pigs fed the SBH diet tended (P = 0.10) to have a greater ADG than pigs fed the WM diet, and energy retention was greater (P < 0.05) for pigs fed the basal diet than for pigs fed the WM diet. The NE of the basal diet fed to growing pigs was greater (P < 0.01) than the NE of the diets containing SBH or WM, and there was a tendency for a greater (P = 0.05) NE of the basal diet than of the other diets when fed to finishing pigs. The NE of SBH did not differ from the NE of WM in either growing or finishing pigs, and there was no interaction between ingredients and stage of growth on the NE of diets or ingredients. The NE of diets for growing pigs (1,668 kcal/kg) was not different from the NE of diets for finishing pigs (1,823 kcal/kg), and the NE of the diets containing SBH (1,688 kcal/kg) was not different from the NE of the diets containing WM (1,803 kcal/kg). Likewise, the NE of SBH (603 kcal/kg) did not differ from the NE of WM (987 kcal/kg). In conclusion, inclusion of 30% SBH or WM decreases the performance and nutrient retention in growing pigs but has little impact on finishing pigs. The NE of the diets decreases with the inclusion of SBH and WM, but the NE of diets and ingredients is not affected by the BW of pigs. The NE of SBH is not different from the NE of WM.

Net energy of soybean oil and choice white grease in diets fed to growing and finishing pigs

The objectives of this experiment were 1) to determine the NE of soybean oil (SBO) and choice white grease (CWG) fed to growing and finishing pigs, 2) to evaluate the effects of inclusion rate of SBO on the NE by growing and finishing pigs, and 3) to determine if there is a difference in the NE of SBO and CWG between growing and finishing pigs. Forty-eight growing (initial BW: 22.13 ± 1.78 kg) and 48 finishing (initial BW: 84.17 ± 5.80 kg) barrows were used, and they were housed and fed individually. Within each stage of growth, pigs were allotted to 8 outcome groups of 6 barrows based on BW. Within each outcome group, pigs were randomly allotted to 1 of 6 groups. Two groups at each stage of growth served as an initial slaughter group. Pigs in the remaining groups were assigned to 4 dietary treatments and slaughtered at the conclusion of the experiment. The basal diet contained corn, soybean meal, and no supplemental lipids. Three additional diets were formulated by mixing 95% of the basal diet and 5% SBO, 90% of the basal diet and 10% SBO, or 90% of the basal diet and 10% CWG. Average daily gain and G:F for finishing pigs and apparent total tract digestibility of energy for growing and finishing pigs increased (linear, P < 0.05) with lipid content, but was not affected by lipid source. The lipid gain:protein gain ratio and the energy retention also increased (linear, P ≤ 0.05) with lipid content in growing and finishing pigs. There were no interactive effects between lipid content and stage of growth or between lipid source and stage of growth on the NE of diets and the NE of dietary lipids. The NE of diets increased (linear, P < 0.01) with increasing SBO (2,056, 2,206, and 2,318 kcal/kg for diets containing 0, 5, or 10% SBO). The NE of the diet containing 10% CWG (2,440 kcal/kg) was greater (P < 0.05) than the NE of the diet containing 10% SBO. The NE of diets was greater (P < 0.05) for finishing pigs than for growing pigs regardless of lipid content or source. The NE of SBO included at 5% (5,073 kcal/kg) was not different from the NE of SBO included at 10% (4,679 kcal/kg), but the NE of CWG (5,900 kcal/kg) was greater (P < 0.05) than the NE of SBO. The stage of growth had no impact on the NE of SBO or CWG. In conclusion, the NE of lipids is not affected by the content of dietary lipids, but the NE of CWG is greater than the NE of SBO.

Intraarticular injection of anakinra in osteoarthritis of the knee: a multicenter, randomized, double-blind, placebo-controlled study

OBJECTIVE

To evaluate the clinical response, safety, and tolerability of a single intraarticular injection of anakinra in patients with symptomatic osteoarthritis (OA) of the knee.

METHODS

Patients with OA of the knee were enrolled in a multicenter, double-blind, placebo-controlled study and randomized 2:1:2 to receive a single intraarticular injection of placebo, anakinra 50 mg, or anakinra 150 mg in their symptomatic knee. Patients were evaluated for 12 weeks postinjection. The primary end point was the change in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score from baseline to week 4. Safety assessments included the evaluation of adverse events (AEs), laboratory tests, and vital signs. Pharmacokinetic parameters were assessed in a subset of patients.

RESULTS

Of 170 patients who enrolled, 160 (94%) completed the study. The mean improvements from baseline to week 4 in the WOMAC score were not statistically different between the placebo group and the patients who received 50 mg of anakinra (P = 0.67) or 150 mg of anakinra (P = 0.77). Anakinra was well tolerated. No withdrawals due to AEs or serious AEs, and no serious infections or deaths were reported. No clinically significant trends were noted in laboratory values or vital signs. Pharmacokinetic parameters demonstrated that the mean terminal half-life of anakinra in serum after intraarticular injection was approximately 4 hours.

CONCLUSION

Anakinra was well tolerated as a single 50-mg or 150-mg intraarticular injection in patients with OA of the knee. However, anakinra was not associated with improvements in OA symptoms compared with placebo.

The effect of ractopamine supplementation at 5 ppm of swine finishing diets on growth performance, carcass composition and ultimate pork quality

Five hundred thirty-six finishing pigs were placed on experiment for an average of 26 d prior to slaughter, to determine the effects of 5 mg ractopamine hydrochloride (RAC) per kg of diet on growth performance, carcass composition and the eating quality of pork. Treatments included a control diet similar to a western Canadian commercial finishing diet and a treatment diet containing 5 mg RAC kg-1 with elevated amino acids, vitamins and minerals. The experiment started when average animal weight was 86 kg; pigs were marketed at an average liveweight of 118 kg. Two pigs were selected from each of 32 pens in week 4 of the experiment, for detailed carcass and meat quality evaluation, providing 16 pigs per gender per treatment. RAC-fed pigs reached market weight 4 d sooner (P < 0.05), grew 13 % faster (P < 0.05) and had 13% better feed efficiency (P < 0.05) than the controls. RAC-fed pigs also had 1 mm less backfat and 2.5 mm thicker loins (P < 0.05). Ultimate pH, purge loss and visual colour scores were unaffected by treatment but RAC-fed pigs had lower CIE a* and b* measurements (P < 0.05). RAC had no effect on juiciness, flavour, saltiness or overall acceptability (P > 0.10), but increased Warner-Bratzler shear force and reduced taste panel tenderness slightly (P < 0.05). The inclusion of 5 mg RAC kg-1 in a commercial finishing diet will increase the rate and efficiency of gain and improve carcass composition. Minimal impact on pork quality can also be expected with the use of RAC fed at this level. Key words: Ractopamine, swine, carcass composition, pork quality, beta-adrenergic agonist

Response to dietary digestible energy concentration in growing pigs fed cereal grain-based diets

Understanding how energy is utilized by the pig, and how the pig responds to changes in dietary energy concentration, is essential information in determining the optimal concentration of dietary energy under farm conditions, which are often highly diverse. The objective of these experiments was to determine how changes in dietary DE concentration, achieved through graded changes in diet composition, would affect the performance and carcass composition of growing pigs. In Exp. 1, which was conducted in a research facility, 300 pigs (31.1 +/- 2.6 kg) were assigned to diets containing 3.09, 3.24, 3.34, 3.42, or 3.57 Mcal of DE/kg. Experiment 2, which was conducted at a commercial swine farm, involved 720 pigs (36.8 +/- 5.9 kg) assigned to diets containing 3.12, 3.30, or 3.43 Mcal of DE/kg. Increased DE concentration was attained by using more wheat, soybean meal, and fat and less barley; true ileal lysine was adjusted as DE increased, and minimal AA:lysine ratios were maintained. In Exp. 1, ADG improved linearly as the energy content of the diet increased (P = 0.03). Feed intake decreased (P < 0.001) and feed efficiency and daily caloric intake improved (P = 0.005) with increased DE content. Variability in growth was not affected by treatment. Carcass index and LM thickness were not affected by increasing dietary DE content; backfat thickness, however, was increased (P < 0.001). In Exp. 2, overall ADG was unaffected by dietary energy content, although an improvement in growth was observed until the pigs reached approximately 80 kg of BW. Overall feed intake decreased with increasing energy content (P = 0.01), although this was not observed during the initial 6 wk of the experiment. Carcass index, lean yield, and backfat were not affected by increasing dietary energy content, whereas LM thickness tended to increase (P = 0.08). The value per pig was unaffected by increasing dietary energy content in both experiments, and returns above feed costs were reduced. Increasing the energy density of the diet for growing pigs through incremental changes in dietary composition had a variable impact on overall growth performance and carcass quality. Increasing the dietary DE had no effect on variations in BW at the time of marketing.

Protective effects of licofelone, a 5-lipoxygenase and cyclo-oxygenase inhibitor, versus naproxen on cartilage loss in knee osteoarthritis: a first multicentre clinical trial using quantitative MRI

OBJECTIVE

In a multicentre study to explore the effects of licofelone as a disease-modifying osteoarthritis drug in comparison with naproxen in patients with knee osteoarthritis (OA), using MRI and x-ray examination.

METHODS

Patients with knee OA (n = 355) were randomised to receive either licofelone (200 mg twice a day) or naproxen (500 mg twice a day). MRI and x-ray examinations were performed at baseline, 6 months (MRI only), 12 and 24 months. MRI was used to assess quantitatively changes in cartilage volume, and x-ray examinations (Lyon-Schuss) to measure changes in the mean and minimum joint space width (JSW) in the medial compartment. Questionnaires probing symptoms were completed. Data were presented as intention to treat (ITT) and according to protocol (ATP).

RESULTS

Cartilage volume loss in the global joint and medial and lateral compartments was significantly less in the licofelone than in the naproxen group for ITT at 12 and 24 months and for ATP at all times except in the medial compartment. Patients with medial meniscal extrusion had a greater loss of cartilage volume. In these patients, licofelone markedly reduced the cartilage loss for both ITT and ATP at 12 and 24 months. Although licofelone showed less reduction in the JSW than naproxen, this did not reach significance. All clinical variables were improved at 24 months (p<0.001) for both groups, with a good safety profile.

CONCLUSION

Licofelone and naproxen were equally effective in reducing OA symptoms; however, licofelone significantly reduced cartilage volume loss over time, thus having a protective effect in patients with knee OA. This study proves the superiority of quantitative MRI over x-ray examinations in a multicentre clinical trial.

Prepartum Nutrition Alters Fatty Acid Composition in Plasma, Adipose Tissue, and Liver Lipids of Periparturient Dairy Cows

The fatty acyl profile of phospholipids (PL) determines the fluidity of cell membranes and affects cell function. The degree to which long-chain fatty acid (LCFA) composition of PL and triacylglycerols (TG) in liver and total lipids in adipose tissue can be altered by prepartum nutrition in peripartal dairy cows is unclear. Multiparous Holsteins (n = 25) were assigned to 1 of 4 prepartal diets: 1) CA, the control diet fed to meet 120% of energy requirements; 2) CR, a control diet fed to meet 80% of requirements; 3) S, a diet supplemented with mostly saturated free fatty acids (47% 16:0, 36% 18:0, 14% cis-18:1) and fed to meet 120% of requirements; or 4) U, a diet similar to S except that cows were abomasally infused with soybean oil so that the diet plus infused fat would meet 120% of requirements. Diets were fed for 40 d prepartum; all cows received a lactation diet postpartum. Groups CR and U had lower prepartum intakes of dry matter and net energy, but glucose concentrations in plasma were similar among treatments. Cows fed S, U, or CR had greater nonesterified fatty acids in plasma prepartum, but cows fed U had decreased beta-hydroxybutyrate postpartum. Postpartal concentrations of total lipids and glycogen in liver tissue were similar among treatments. Cows in group U had a greater percentage of 18:2 but less 16:0, 18:0, and 20:4 in plasma total lipids than cows fed S. Treatment U increased 18:2 and 18:3 and decreased 18:1 in subcutaneous adipose tissue at 1 d postpartum. Across diets, percentages of 16:0 and trans-18:1 were increased, and 18:0, 20:3, and 20:5 were decreased, in hepatic PL at d 1 postpartum. Significant treatment x time interactions indicated that treatment U increased 18:2 in hepatic PL at the expense of 18:1, 20:3, 20:4, 22:6, and 24:0 on d 1 postpartum, but changes were normalized by d 65 postpartum. The unsaturation index of hepatic PL was lower at d 1 than at d -45 or 65, which implies that hepatic membrane fluidity decreased around parturition. The unsaturation index at d 1 was greater for cows fed S than those fed CA or U. Percentages of 16:0, 18:1, and 22:0 were increased, and 18:0, 20:3, 20:4, 20:5, 24:0, and 26:0 were decreased, in hepatic TG at d 1. Prepartal feed restriction modestly affected tissue LCFA profiles. The LCFA profile of adipose tissue, liver PL, and liver TG can be altered by dietary LCFA supply prepartum; changes in liver are normalized by 65 d postpartum.

Factors affecting the concentration of sphingomyelin in bovine milk

Sphingomyelin is a phospholipid located in the outer leaflet of the plasma membrane of most cells and is a component of the milk fat globule membrane. Sphingomyelin and its digestion products participate in several antiproliferative pathways that may suppress oncogenesis. Although milk and dairy products are important sources of sphingomyelin in the human diet, little is known about factors that influence sphingomyelin concentrations in milk fat or whether concentrations can be modified via the nutrition of cows. Sphingomyelin concentrations were determined in milk from Holstein and Jersey cows matched for parity and stage of lactation. Sphingomyelin was more concentrated in milk fat from Holstein cows than in milk fat from Jersey cows (1,044 vs. 839 microg/g of fat). Concentrations in whole milk did not differ because of greater milk fat content for milk from Jerseys. Differences between breeds may be related to the greater fat globule size in milk from Jerseys. Sphingomyelin content in whole milk increased with increasing days in milk because of associated increases in milk fat content. Regardless of breed, primiparous cows had greater amounts of stearic acid and less palmitic acid in sphingomyelin than did older cows. The sphingomyelin concentration in milk fat of cows in a commercial Jersey herd was lower for cows in their fourth or greater parity. Sphingomyelin content in whole milk was greater for cows in late lactation because of greater milk fat content. Feed restriction of multiparous Holstein cows to 37% of ad libitum dry matter intake increased milk fat content but did not affect milk sphingomyelin content or milk fat globule size. Supplementation of the diet with 4% soybean oil did not affect milk composition, sphingomyelin content, or milk fat globule size. Milk was sampled seasonally from 7 herds throughout Illinois during a 2-yr period. Sphingomyelin concentration in milk fat was greatest during summer and least during winter, but whole milk concentrations did not vary across seasons. We conclude that 1) sphingomyelin content of milk fat is greater in milk from Holsteins than that from Jerseys, 2) sphingomyelin content in whole milk increases with stage of lactation, and 3) sphingomyelin content of milk fat is greater during summer. However, efforts to produce milk with a greater sphingomyelin content through altering management and nutrition are unlikely to be successful.

Effect of diet composition on water consumption in growing pigs1

Concerns relating to use of water resources by the livestock industry, combined with the rising cost of manure management, have resulted in greater interest in identifying ways to reduce drinking water utilization by pigs while maintaining animal well-being and achieving satisfactory growth performance. The objective of this experiment was to determine if increasing the dietary CP or mineral concentrations increases water intake and excretion and, conversely, if reducing the dietary CP content reduces water intake and excretion. Forty-eight barrows (34.3 +/- 4.6 kg of BW; 12/treatment) were given free access to diets containing a low protein (16.9% CP), high protein (20.9% CP), or excess protein (25.7% CP) level, or a diet with excess levels of Ca, P, Na, and Cl. Water was available to each pig on an ad libitum basis via dish drinkers that were determined to waste less than 3% of total water flow. The excess CP diet tended to increase average daily water intake (ADWI) and urinary excretion (P < 0.10) and increased the water:feed ratio (P < 0.05); lowering dietary CP did not lower water intake or excretion. The excess mineral diet did not increase ADWI or urinary excretion but did increase water excretion via the feces. Daily nutrient intake and dietary nutrient concentration were poor predictors of ADWI; only daily intake of N and K were significantly correlated with ADWI (P < 0.05), and the r-values were low (0.39 and 0.32, respectively). There was no relationship between ADFI and ADWI. The average water:feed ratio was 2.6:1. Any study of water utilization is complicated by behavioral as well as nutritional and physiological influences, and isolating physiological need from so-called luxury intake is a significant experimental challenge. Because the impact of dietary treatment on water utilization was small, we conclude that factors other than dietary protein and mineral concentration and daily protein and mineral intake have a relatively large effect on water intake and excretion. Consequently, strategies to reduce water intake must recognize, understand, and manage these additional behavioral and physiological factors. Diet composition may be a part of strategies designed to reduce excessive water utilization by the pig industry but may have a limited effect if other important factors are ignored.

The effects of dietary energy concentration and weaning site on weanling pig performance1

This study was conducted to evaluate the effects of dietary energy density and weaning environment on pig performance. Treatment diets were formulated to vary in DE concentration by changing the relative proportions of low (barley) and high (wheat, oat groats, and canola oil) energy ingredients. In Exp. 1, 84 pigs in each of 3 replications, providing a total of 252 pigs, were weaned at 17 x 2 d of age and randomly assigned to either an on-site or an off-site nursery and to 1 of 3 dietary DE concentrations (3.35, 3.50, or 3.65 Mcal/kg). Each site consisted of a nursery containing 6 pens; 3 pens housed 7 barrows and 3 housed 7 gilts. All pigs received nontreatment diets in phase I (17 to 19 d of age) and phase II (20 to 25 d of age), respectively. Dietary treatments were fed from 25 to 56 d of age. Off-site pigs were heavier at 56 d of age (23.4 vs. 21.3 kg; P < 0.05) and had greater ADFI (0.77 vs. 0.69 kg/d; P < 0.01) than on-site pigs. There was a linear decrease in ADG (P < 0.01) and ADFI (P < 0.001) with increasing DE concentration. Efficiency of gain improved (P < 0.01) with increasing DE concentration. There was no interaction between weaning site and diet DE concentration, indicating that on-site and off-site pigs responded similarly to changes in diet DE concentration. In Exp. 2, nutrient digestibility of the treatment diets used in Exp. 1 was determined using 36 pigs with either ad libitum or feed intake restricted to 5.5% of BW. Energy and N digestibility increased (P < 0.001) with increasing DE concentration. Nitrogen retention and daily DE intake increased with DE concentration in pigs fed the restricted amount of feed (P < 0.05). These results indicate that weaning off-site improves pig weight gain. The weanling pig was able to compensate for reduced dietary DE concentration through increased feed intake. Growth limitation in the weanling pig may not be overcome simply by increasing dietary DE concentration.

Dry matter intake is decreased more by abomasal infusion of unsaturated free fatty acids than by unsaturated triglycerides

Previous experiments from our group have demonstrated that abomasal infusion of unsaturated free fatty acids (FFA) markedly decreases dry matter intake (DMI) in dairy cows. In contrast, experiments from other groups have noted smaller decreases in DMI when unsaturated triglycerides (TG) were infused postruminally. Our hypothesis was that unsaturated FFA would be more potent inhibitors of DMI than an equivalent amount of unsaturated TG. Four Holstein cows in late lactation were used in a single reversal design. Cows were fed a total mixed ration containing (DM basis) 23% alfalfa silage, 23% corn silage, 40.3% ground shelled corn, and 10.5% soybean meal. Two cows received soy FFA (UFA; 0, 200, 400, 600 g/d) and 2 received soy oil (TG) in the same amounts; cows then were switched to the other lipid source. Cows were abomasally infused with each amount for 5-d periods. The daily amount of lipid was pulse-dosed in 4 equal portions at 0600, 1000, 1700, and 2200 h; no emulsifiers were used and there was no sign of digestive disturbance. Both lipid sources linearly decreased DMI, with a significant interaction between lipid source and amount. Slope-ratio analysis indicated that UFA were about 2 times more potent in decreasing DMI than were TG. Decreased DMI led to decreased milk production. Milk fat content was increased linearly by lipid infusion. Milk fat yield decreased markedly for UFA infusion but was relatively unaffected by infusion of TG. Contents of short- and medium-chain fatty acids in milk fat decreased as the amount of either infusate increased. Contents of C(18:2) and C(18:3) in milk fat were increased linearly by abomasal infusion of either fat source; cis-9 C(18:1) was unaffected. Transfer of infused C(18:2) to milk fat was 35.6, 42.5, and 27.8% for 200, 400, and 600 g/d of UFA, and 34.3, 39.6, and 34.0% for respective amounts of TG. Glucagon-like peptide-1 (7-36) amide (GLP-1) concentration in plasma significantly increased as DMI decreased with increasing infusion amount of UFA or TG. Plasma concentration of cholecystokinin-octapeptide (CCK-8) was unaffected by lipid infusion. These results indicate that unsaturated FFA reaching the duodenum are more potent inhibitors of DMI than are unsaturated TG; the effect may be at least partially mediated by GLP-1.

Isolated canine and murine intestinal cells exhibit a different pattern of fuel utilization for oxidative metabolism

The amount and type of dietary fiber influences the end-products of fermentation and thus fuel availability to intestinal tissue. Metabolic fuel usage was studied in intestinal cells isolated from dogs consuming a commercial diet or from rats consuming either a commercial rat diet or dog diet to examine preferential fuel usage, the effect of diet, and species differences. Production of 14CO2 was measured by incubating cells in media containing either D-[U-14C]glucose, [1-14C]n-butyrate, L-[U-14C]glutamine, or [1-14C]propionate with or without competing substrates. The presence of a mixture of 5 mM each of glucose, butyrate, propionate, and acetate and 1 mM glutamine in the media decreased CO2 production from glucose, glutamine, and propionate by canine enterocytes (P < 0.05) and from glutamine and propionate by canine colonocytes (P < 0.05). The presence of glutamine in the media decreased glucose oxidation by murine enterocytes, regardless of the diet. Similarly, glutamine decreased glucose oxidation by murine colonocytes (P < 0.05), but only when the rats had consumed the rat diet. Regardless of diet, murine colonocytes oxidized more butyrate (P < 0.01) than did enterocytes, and murine enterocytes tended (P < 0.07) to oxidize more glucose than did colonocytes. The proportion of propionate in colonic contents was higher in dogs than in rats (P < 0.02), and the proportion of butyrate tended to be higher in contents from rats than in those from dogs (P < 0.08). Colonic and cecal wet weights were decreased (P < 0.05) when rats were fed the commercial dog diet. Preferred utilization of substrates by isolated canine enterocytes and colonocytes differed from that of murine intestinal cells. These differences were only partially overcome by feeding the same diet to each species.

Concentrations of conjugated linoleic acid (cis-9, trans-11-octadecadienoic acid) are not increased in tissue lipids of cattle fed a high-concentrate diet supplemented with soybean oil

Conjugated linoleic acid (CLA), a mixture of isomers of linoleic acid, has many beneficial effects, including decreased tumor growth in animal cancer models. The cis-9, trans-11 isomer of CLA (CLA9,11) can be formed in the rumen as an intermediate in biohydrogenation of linoleic acid. Recent data, however, indicate that tissue desaturation of trans-fatty acids is an important source of CLA9,11 in milk. Our objective was to determine whether supplementing a high-corn diet with soybean oil (SBO; a source of linoleic acid) would increase concentrations of CLA in ruminal contents and tissue lipids. Four ruminally cannulated steers were utilized in a Latin square design with 28-d periods. A control diet (80% cracked corn, 2.0% corn steep liquor, 8.0% ground corn cobs, and 10% supplement [soybean meal, ground shelled corn, minerals, and vitamins]) was supplemented with 2.5, 5.0, or 7.5% (DM basis) SBO. Supplemental SBO did not affect ruminal pH or concentrations of the major VFA. The proportion and amount (mg FA/g DM ruminal contents) of CLA9,11 were not increased by increasing dietary SBO. However, the proportion and amount of the trans-10, cis-12 CLA isomer (CLA10,12) in ruminal contents increased linearly (P < 0.006) as dietary SBO increased. Trans-18:1 isomers in ruminal contents increased linearly (P < 0.02) as dietary SBO increased. The proportion of CLA10,12 was correlated positively (P < 0.001) with proportions of trans-C 18:1 isomers in ruminal contents. Conversely, CLA9,11 was correlated negatively (P < 0.05) with the proportions of trans-18:1 in ruminal contents. The same high-corn diet, supplemented with 0 or 5% SBO, was fed to 20 Angus-Wagyu heifers for 102 d in a randomized complete block design to determine the effect of added SBO on tissue deposition of CLA. Supplemental SBO did not affect feed intake, gain:feed, or carcass quality. Tissue samples were obtained from the hindquarter, loin, forequarter, liver, large and small intestine, and subcutaneous, mesenteric, and perirenal adipose depots. The concentration of CLA9,11 was greatest in subcutaneous adipose tissue but was not affected in any tissue by SBO. Supplementing high-corn diets with SBO does not increase CLA9,11 concentrations in tissues of fattening heifers. Research is needed to identify regulatory factors for pathways of biohydrogenation that lead to increased concentrations of CLA10,12 in ruminal contents when high-oil, high-concentrate diets are fed.

Responses of milk fat composition to dietary fat or nonstructural carbohydrates in Holstein and Jersey cows

Milk fat from Jersey cows contains less oleic acid (cis-C18:1) and more short- and medium-chain fatty acids than does milk fat from Holstein cows. The objective of this experiment was to determine responses in milk fat composition when Jersey and Holstein cows were fed diets either high (37% of dry matter) or low (27% of dry matter) in content of nonstructural carbohydrates (NSC) and supplemented with either 0 or 2.5% (of dry matter) of a mostly saturated fat source. Four Holstein cows and four Jersey cows were used in a Latin square design with 28-d periods; diets were in a 2 x 2 factorial arrangement. Fat supplementation decreased contents of fatty acids synthesized de novo within the mammary gland and increased contents of C18:0 and cis-C18:1. Low-NSC diets tended to increase C16:0 and to decrease C18:0, cis-C18:1, and C18:3. Despite the differences in fatty acid composition between breeds, both breeds generally responded similarly to dietary treatments. An interaction of breed and fat indicated that the content of cis-C18:1 in milk fat was increased more by supplemental fat in Holsteins than in Jerseys. Interactions of breed x fat and breed x carbohydrate type showed that the ratio of cis-C18:1 to C18:0 decreased when Jerseys were supplemented with fat but increased for Holsteins, and decreased when Jerseys were fed the low-NSC diet but increased when Holsteins were fed low NSC. The data are consistent with the hypothesis (Beaulieu and Palmquist, 1995, J. Dairy Sci. 78:1336-1344) that mammary activity of stearoyl-coenzyme A desaturase is lower in Jerseys than in Holsteins.

Tolerability profiles of rofecoxib (Vioxx) and Arthrotec. A comparison of six weeks treatment in patients with osteoarthritis

OBJECTIVE

To compare the incidence of selected spontaneously reported adverse events (AEs) in patients with osteoarthritis (OA) treated with rofecoxib (VIOXX, 12.5 mg qd) or Arthrotec (diclofenac 50 mg/misoprostol 200 mcg bid).

METHODS

Double-blind, parallel-group, 6-week study of patients aged > or = 40 years with a clinical diagnosis of OA treated with rofecoxib or Arthrotec. Primary endpoint: self-reported diarrhea; secondary endpoints: abdominal pain, discontinuations due to AEs, GI AEs and NSAID-type GI AEs (ie., acid reflux, dyspepsia, epigastric discomfort, heartburn, nausea, vomiting).

RESULTS

Among 483 patients (80.3% females, mean age 62.1), the rofecoxib group vs the Arthrotec group respectively reported diarrhea 6.2% vs 16.2% (p<0.001); drug-related diarrhea 3.7% vs 16.2% (p<0.001); one or more clinical AEs 52.9% vs 73.0% (p<0.001); GI AEs 28.9% vs 48.5% (p<0.001); NSAID-type GI AEs 18.6% vs 29.9% (p=0.004); discontinuations due to abdominal pain 0.4% vs 3.7% (p<0.05); and discontinuations due to any AE 4.1% vs 9.1% (p=0.029). No significant differences were observed in efficacy.

CONCLUSION

Rofecoxib 12.5 mg qd has improved GI tolerability and similar efficacy compared to Arthrotec (diclofenac 50 mg/misoprostol 200 mcg bid).

Efficacy and safety of diacerein in osteoarthritis of the knee: a double-blind, placebo-controlled trial. The Diacerein Study Group

OBJECTIVE

To evaluate the efficacy and safety of diacerein, a drug with interleukin-1beta--inhibitory activity in vitro, in patients with knee osteoarthritis (OA).

METHODS

A total of 484 patients fulfilling the American College of Rheumatology criteria for knee OA were enrolled in this 16-week, randomized, double-blind, placebo-controlled, parallel study group with 3 diacerein dosages of 50 mg/day, 100 mg/day, and 150 mg/day (administered twice daily).

RESULTS

In the intent-to-treat population, 100 mg/day diacerein (50 mg twice daily) was significantly superior (P < 0.05) to placebo using the primary criterion (visual analog scale [VAS] assessment of pain on movement). Significant improvement (P < 0.05) was also observed for the secondary criteria, which included the Western Ontario and McMaster Universities OA Index (WOMAC), the WOMAC subscores, and the VAS assessment of handicap. In patients treated with diacerein dosages of 50 mg/day and 150 mg/day, favorable but not significant results were observed for the primary criterion. The best daily dosage of diacerein, calculated from the effect on the VAS assessment of pain on movement, was 90.1 mg. In the per-protocol population, the analysis of the primary criterion showed significant dose-dependent differences (P < 0.05) between each of the 3 diacerein dosages and the placebo. No differences were observed among the 3 diacerein groups. A significantly higher incidence (P < 0.05) of adverse events (AEs), as well as a higher rate of dropoout due to AEs, was observed in patients treated with 150 mg/day diacerein versus those treated with placebo, 50 mg/day diacerein, or 100 mg/day diacerein. Mild-to-moderate transient changes in bowel habits were the most frequent AEs, increasing with the dosage.

CONCLUSION

Diacerein, a drug for the treatment of OA, was shown to be an effective treatment for symptoms in patients with knee OA. Taking into account both efficacy and safety, the optimal daily dosage of diacerein for patients with knee OA is 100 mg/day (50 mg twice daily).

Effects of saturation and esterification of fat sources on site and extent of digestion in steers: digestion of fatty acids, triglycerides, and energy

Five steers (mean BW 526 kg) fitted with ruminal, duodenal, and ileal cannulas were used in a 5 x 6 Youden square design with 14-d periods. Diets contained chopped alfalfa hay, corn silage, and concentrate (25:35:40, DM basis). Treatments were 1) control (no added fat); 2) tallow (T), iodine value (IV) = 51.5; 3) partially hydrogenated tallow (PHT), IV = 30.7; 4) hydrogenated tallow (HT), IV = 6.9; 5) blend (1: 1) of HT and hydrogenated free fatty acids (HTHFA), IV = 9.0; and 6) hydrogenated free fatty acids (HFA), IV = 11.2. Fats replaced cornstarch in the control diet to supply 5% added fatty acids. Intake was restricted to 90% of ad libitum; DMI was similar among diets (mean 9 kg/d). Total fatty acid intake averaged 170, 500, 506, 525, 489, and 491 g/d for treatments 1 to 6, respectively. Flows of total C16, total C18, and total fatty acids to the duodenum were increased by supplemental fat; flows of total C18 and total fatty acids were greater than their intake for all treatments. Flow of total fatty acids associated with ruminal bacteria accounted for 50 and 17% of the total duodenal fatty acid flow for the control and fat-supplemented diets, respectively. Digestibility of total fatty acids entering the small intestine (74, 71, 62, 39, 53, and 63% for treatments 1 to 6, respectively) was greater for the control diet than for fat-supplemented diets and decreased as either saturation (T < PHT < HT) or esterification (HFA < HTHFA < HT) increased. Digestibilities of fatty acids in the total tract followed similar patterns. Ruminal lipolysis of dietary triglycerides decreased linearly as the degree of saturation of fat sources increased. Small intestinal disappearance of triglycerides (89, 75, 51, 44, 64, and 73% of duodenal flow for treatments 1 to 6, respectively) decreased linearly as either saturation or esterification increased. Flows and digestion of gross energy followed patterns similar to those for fatty acids and triglycerides. Resistance to ruminal and small intestinal lipolysis is a major factor contributing to the poor digestibility of highly saturated triglycerides.

Substrate utilization for hepatic gluconeogenesis is altered by increased glucose demand in ruminants

Hepatocytes isolated from 10 Dorset wethers that were treated with excipient or 1.0 g/d of phlorizin for 72 h were used to determine the effects of increased glucose demand on utilization of [1-(14)C]propionate and [1-(14)C] alanine for oxidative metabolism and gluconeogenesis. Control and phlorizin-treated wethers excreted 0 and 62.8 g/d of glucose into the urine, respectively. Phlorizin treatment tended to increase conversion of propionate and alanine to CO2. A phlorizin x substrate interaction for conversion to glucose indicated that conversion of alanine to glucose was increased more by phlorizin treatment than was conversion of propionate (285 vs 166% of controls). Phlorizin treatment did not affect estimated Ks for conversion of substrates to either CO2 or glucose; however, phlorizin increased estimated Vmax for conversion of substrates to CO2 and tended to increase estimated Vmax for conversion of substrates to glucose. Phlorizin treatment slightly increased the ratio of conversion of propionate to glucose compared with CO2 and slightly decreased the ratio of conversion of alanine to glucose compared with CO2. In vitro addition of 2.5 mM NH4Cl decreased conversion of propionate to CO2 and glucose but had little effect on conversion of alanine to CO2 and glucose. Estimated Ks and Vmax for conversion of substrates to CO2, Ks for conversion of substrates to glucose, and Vmax for conversion of alanine to glucose were not affected by NH4Cl; however, Vmax for conversion of propionate to glucose was decreased by NH4Cl. These data indicate that although utilization of propionate for gluconeogenesis is extensive, amino acids have the potential to increase in importance as gluconeogenic substrates when glucose demand is increased substantially. Furthermore, excess ammonia decreases the capacity of hepatocytes to utilize propionate for oxidation and gluconeogenesis.

Granulocyte-macrophage colony-stimulating factor modulates tapasin expression in human neutrophils

Differential display-polymerase chain reaction (DD-PCR) was used to evaluate changes in mRNA expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) treated human neutrophils to better understand how this cytokine affects the functions of neutrophils at the molecular level. Although a variety of cDNA fragments were identified as modulated by GM-CSF with the use of DD-PCR, one fragment in particular, NGS-17 (neutrophil GM-CSF-stimulated fragment #17), was characterized. The NGS-17 fragment hybridized to a 3.8-kh mRNA that encodes for a protein of a predicted molecular mass of 47.6 kDa. After cloning and sequencing, this gene was found to code for the recently sequenced tapasin or TAP-A protein. Immunoprecipitation and immunoblotting studies using anti-tapasin antibodies showed that tapasin is expressed in neutrophils and is associated with the MHC class I-TAP complex. Moreover, tapasin expression was found to be induced by dimethyl sulfoxide and by retinoic acid in HL-60 cells. This is the first report on the expression of tapasin in human neutrophils. It provides novel information, at the molecular level, on how GM-CSF enhances the functions of these cells.

Metabolic adaptation to experimentally increased glucose demand in ruminants

Four Dorset wethers were studied in a Latin square design with 72-h periods to determine the metabolic adaptations that occur in support of increased glucose demand in ruminants. Wethers injected at 8-h intervals with excipient or a total of .5, 1.0, or 2.0 g/d of phlorizin excreted an average of 0, 72.7, 97.9, and 98.5 g/d of glucose into the urine, respectively. Both acute (2 to 24 h after the first injection) and chronic (8-h intervals from 8 to 72 h after the first injection) adaptations of plasma variables to phlorizin treatment were assessed. Concentrations of plasma glucose decreased linearly with increasing phlorizin dose during the 1st 24 h of treatment and tended to decrease linearly with phlorizin dose during 8 to 72 h of treatment. Urea N tended to increase linearly during 2 to 24 h and increased linearly during 8 to 72 h. Nonesterified fatty acids increased linearly with phlorizin injection during the entire treatment period. beta-Hydroxybutyrate increased quadratically with phlorizin injection during 2 to 24 h and tended to increase quadratically during 8 to 72 h. The ratio of insulin to glucagon tended to decrease linearly with phlorizin injection during the 1st 24 h but was unaffected from 8 to 72 h. Triiodothyronine, but not thyroxine, tended to decrease linearly with phlorizin injection during 8 to 72 h. Cortisol was not affected by treatment. Digestibilities of energy and N were not affected by treatment. Urinary energy excretion increased with phlorizin injection in proportion to the amounts of glucose excreted into the urine. These data indicate that phlorizin-treated wethers largely adapted to phlorizin treatment by 24 h after the first injection and are a suitable model for further investigations of hepatic adaptation to increased glucose demand in ruminants.

ABC50, a novel human ATP-binding cassette protein found in tumor necrosis factor-alpha-stimulated synoviocytes

We have used the recently developed technique of differential display polymerase chain reaction to seek for new genes modulated by tumor necrosis factor-alpha (TNF-alpha) in cultured synoviocytes. One PCR fragment was shown to correspond to a new gene that was mapped by high-resolution fluorescence in situ hybridization to band 6p21.33. The cDNA of this gene was cloned, and the deduced amino acid sequence revealed consensus motifs for the nucleotide binding folds of the ATP-binding cassette (ABC) family of proteins. However, a hydropathy curve showed that the polypeptide does not contain the transmembrane domains that are typical of the subfamily of ABC transporters and are associated with transporter/channel functions. The new gene, called ABC50, is the first human and mammalian ABC protein found to lack transmembrane domains. Homology with some yeast ABC proteins suggests that ABC50 codes for a new human ribosomal protein involved in translation of mRNA. It could therefore play a role in the enhancement of protein synthesis that follows TNF-alpha treatment of synoviocytes and thus participate in the inflammatory processes mediated by this cytokine. Furthermore, since TNF-alpha also modulates the expression of MHC class I genes, and these genes are known to map to 6p21.33, it is hypothesized that ABC50 and MHC class I are part of the same chromatin expression domain.

Human neutrophils express the interleukin-15 receptor alpha chain (IL-15Ralpha) but not the IL-9Ralpha component

The interleukin-15 receptor (IL-15R) is composed of at least three chains, namely gammac, IL-2Rbeta, and the recently identified IL-15Ralpha, while the IL-9R complex consists of gammac and a subunit designated IL-9Ralpha. Our previous work and that of others have shown that human neutrophils express gammac and IL-2Rbeta (two components shared with IL-2R) but not IL-2Ralpha and that IL-15 is a neutrophil agonist, whereas IL-2 is not. In this study, using flow cytometry with a specific anti-human IL-15Ralpha, we show for the first time that human neutrophils express surface IL-15Ralpha. Although we previously found that IL-15 is a neutrophil agonist, our present work shows that IL-15 does not trigger superoxide production nor cell spreading onto glass. In addition, we report that human neutrophils do not respond to IL-9 with respect to the functions/responses studied, namely, superoxide production, spreading onto glass, cell shape changes, phagocytosis, RNA synthesis, and apoptosis. Further, our results show that neutrophils do not express IL-9Ralpha as assessed by flow cytometry with a specific anti-human IL-9Ralpha antibody that stains the transfected cell line BW-h9R used as positive control. Finally, our results indicate that gammac expression was not modulated and remained stable for up to 24 h when neutrophils were stimulated with all currently known "gammac users," namely, IL-2, IL-4, IL-7, IL-9, and IL-15. We conclude that human neutrophils express all IL-15R components on their surface, including IL-15Ralpha, that IL-15 activates human neutrophils (as the IL-4 neutrophil agonist) by a mechanism which does not involve upregulation of gammac cell surface expression, and that IL-9 is not a neutrophil agonist as demonstrated by the inability to modulate the tested functions/responses that correlate with lack of the IL-9R component, namely, IL-9Ralpha.

Responsiveness of human neutrophils to interleukin-4: induction of cytoskeletal rearrangements, de novo protein synthesis and delay of apoptosis

Interleukin-4 (IL-4) and IL-13 are cytokines that share many biological activities. We have previously demonstrated that IL-13 affects a number of neutrophil responses, and here we extend our observations to IL-4. We present, for the first time, direct evidence for the presence of functional IL-4 receptors on human neutrophils. We report that IL-4 induces RNA synthesis in a concentration-dependent manner and, based on observations of the induction of morphological cell shape changes and spreading onto glass, we demonstrate that IL-4 activates neutrophil cytoskeletal rearrangements. We further show that IL-4 is a potent activator of de novo protein synthesis in neutrophils, and we identify by microsequencing one of these proteins as the cytoskeletal protein actin. We were also able to demonstrate for the first time that actin is cleaved into at least two fragments of approximately 30 kDa (pI 5.4) and approximately 25 kDa (pI 5.0) in neutrophils. Finally, we report that IL-4 delays neutrophil apoptosis, as assessed by morphological observations from cytocentrifuge preparations, as well as by measurement of differences in staining by flow cytometry with both propidium iodide and Hoechst reagent. Taken together, we conclude that IL-4 is a more potent neutrophil agonist than previously believed. We discuss the possibility that the induction of the de novo synthesis of actin by IL-4 is related to the mechanism by which this cytokine delays apoptosis; in addition, the cleavage of this protein is likely to contribute to the apoptotic process.

Absence of the IL-7 receptor component CDw127 indicates that gamma(c) expression alone is insufficient for IL-7 to modulate human neutrophil responses

It has been proposed that neutrophils are targets for interleukin-7 (IL-7) because this cytokine was found to increase the number of murine immature neutrophils in vivo. In addition, some nonhuman myeloid cell lines were shown to express the IL-7 receptor (IL-7R). Moreover, it was recently discovered that human neutrophils constitutively express the common gamma chain (gamma(c)), known to be a component of not only IL-7R, but also IL-2R, IL-4R, IL-9R, and IL-15R. Among these, we have recently observed that IL-4 and IL-15 are neutrophil agonists. All of the above observations prompted us to study IL-7-human neutrophil interactions. In this study, we investigated potential effects of IL-7 on a range of neutrophil responses. Although we were able to confirm the presence of the gamma(c) component on human neutrophils, we report, for the first time, that these cells lack the CDw127 component of IL-7R. When studying potential modulatory effects of IL-7 on human neutrophils, we found that IL-7 does not induce respiratory burst, phagocytosis, or cytoskeletal functions and does not alter gene expression. Positive controls were included in each assay and the expected results were obtained. In addition, in contrast to IL-4 and IL-15, we found that neutrophil apoptosis is not modulated by IL-7, while granulocyte-macrophage colony-stimulating factor, used here as control, strongly delayed this process as expected. We conclude that the sole expression of gamma(c) on human neutrophils is insufficient to modulate neutrophil responses with respect to the studied functions. Therefore, it cannot be proposed, based on studies performed with nonhuman cells or cell lines, that human neutrophils are targets for IL-7.

Tracing gluconeogenesis with deuterated water: measurement of low deuterium enrichments on carbons 6 and 2 of glucose

The contribution of gluconeogenesis to glucose production in vivo can be measured by enriching body water with 0.5% 2H2O and measuring the glucose labeling ratio C6/C2 (Landau et al., J. Clin. Invest. 95, 172-178, 1995). We present further refinements of the measurements of the 2H enrichments on C6 and C2 of glucose. The transfer of 2H from C6 of glucose to hexamethylenetetramine (HMT) and extraction in preparation for gas chromatography-mass spectrometry can be done in a single test tube, without distillation of the intermediate formaldehyde. In addition, extraction of small amounts of HMT is greatly improved by making a HMT-iodine adduct. For C2, glucose is reduced to sorbitol, and 2H on C2 is transferred enzymatically to [U-13C3]pyruvate, forming [U-13C3,2-2H]lactate. The latter is assayed by negative chemical ionization gas chromatography-mass spectrometry of the pentafluorobenzyl derivative. The natural enrichment of the [U-13C3]lactyl ion is only 0.4%, allowing measurements of 2H enrichment down to 0.1%. These techniques were used in dogs infused with 2H2O and in isolated rat livers perfused with buffer containing 1 to 5% 2H2O. Our data reveal a difference in the rate of labeling of C6 and C2 of glucose in vivo. Lastly, in cows infused with [6,6-2H2]glucose, we show that the turnover of glucose can be economically measured by assaying low tracer enrichment (down to 0.1%) via hexamethylenetetramine.

Differential effects of interleukin-15 (IL-15) and IL-2 on human neutrophils: modulation of phagocytosis, cytoskeleton rearrangement, gene expression, and apoptosis by IL-15

Human neutrophils have been shown recently to express both the beta and the gamma chains of the interleukin-2 receptor (IL-2R). IL-15, a cytokine that has recently been cloned and characterized, was found to share many of the biological functions of IL-2 and is known to mediate signals through IL-2R beta and IL-2R gamma. In recent studies, we observed that IL-2 exerts few effects on various neutrophil functions, but information on IL-15-neutrophil interactions is lacking. In this study, we observed that IL-15, in contrast to IL-2, induces important morphological cell shape changes that are typical of activated neutrophils. Furthermore, phagocytosis of opsonized sheep red blood cells was significantly increased by IL-15 but not by IL-2. However, similar to IL-2, IL-15 did not modulate the oxidative burst response. Furthermore, we observed that de novo RNA synthesis is increased in neutrophils by IL-15 along with de novo protein synthesis, whereas no significant effect of IL-2 was noted. Among the different proteins that were found to be upregulated by IL-15, one was identified by microsequencing as the cytoskeletal protein actin. Finally, we found that IL-15 delays apoptosis of neutrophils more efficiently than IL-2 when evaluated by both microscopic observations and flow cytometry procedures. Furthermore, this phenomenon was dose-dependent (10 to 500 ng/mL), and, at 500 ng/mL, IL-15 delayed apoptosis as strongly as granulocyte-macrophage colony-stimulating factor. This study is the first to show that IL-15 is a significant neutrophil agonist. Moreover, in view of the differential effects of IL-15 and IL-2 on this cell type, our results support the existence of a specific IL-15R component(s) on human neutrophils.

The IL-1 and IL-1 receptor antagonist (IL-1Ra) response of human neutrophils to EBV stimulation. Preponderance of IL-Ra detection

The present study investigated the effect of EBV on gene expression and protein synthesis of IL-1 and its natural IL-1R antagonist (IL-1Ra) in human peripheral blood neutrophils. EBV induced a rapid accumulation of IL-1 and IL-lRa mRNA in neutrophils that was associated with the later appearance of considerable amounts of IL-1alpha, IL-1beta, and IL-Ra proteins. Approximately 3200 and 610 times more IL-Ra than IL-1alpha a or IL-1beta, respectively, was secreted by neutrophils in response to EBV. The effect induced by EBV cannot reflect an overall metabolic activity of neutrophils, since EBV failed to induce granulocyte-macrophage OF synthesis. Heat-inactivated virus was unable to stimulate cytokine synthesis, whereas UV-irradiated virus retained the full IL-1- and IL-1Ra-inducing potential of the native particle. Furthermore, pretreatment of cells with cycloheximide or phosphonoacetic acid did not abrogate the effect of EBV, suggesting that EBV does not penetrate the cell, but that a virion's structural molecule is required to induce such an effect. In this respect, neutralization of the viral particles with the mAb 72A1, which is known to react with glycoprotein gp350 of the viral envelope, inhibits the production of IL-1 and IL-1Ra, suggesting that gp350 could be involved in this process. Thus, the elevated levels of IL-1Ra detected for EBV-stimulated neutrophils might be part of a mechanism used by the virus to evade the immune system.

The IL-1 and IL-1 receptor antagonist (IL-1Ra) response of human neutrophils to EBV stimulation. Preponderance of IL-Ra detection

The present study investigated the effect of EBV on gene expression and protein synthesis of IL-1 and its natural IL-1R antagonist (IL-1Ra) in human peripheral blood neutrophils. EBV induced a rapid accumulation of IL-1 and IL-lRa mRNA in neutrophils that was associated with the later appearance of considerable amounts of IL-1alpha, IL-1beta, and IL-Ra proteins. Approximately 3200 and 610 times more IL-Ra than IL-1alpha a or IL-1beta, respectively, was secreted by neutrophils in response to EBV. The effect induced by EBV cannot reflect an overall metabolic activity of neutrophils, since EBV failed to induce granulocyte-macrophage OF synthesis. Heat-inactivated virus was unable to stimulate cytokine synthesis, whereas UV-irradiated virus retained the full IL-1- and IL-1Ra-inducing potential of the native particle. Furthermore, pretreatment of cells with cycloheximide or phosphonoacetic acid did not abrogate the effect of EBV, suggesting that EBV does not penetrate the cell, but that a virion's structural molecule is required to induce such an effect. In this respect, neutralization of the viral particles with the mAb 72A1, which is known to react with glycoprotein gp350 of the viral envelope, inhibits the production of IL-1 and IL-1Ra, suggesting that gp350 could be involved in this process. Thus, the elevated levels of IL-1Ra detected for EBV-stimulated neutrophils might be part of a mechanism used by the virus to evade the immune system.

Effects of interleukin-13 on human neutrophil functions

It was recently shown that interleukin-13 (IL-13) induces the expression and release of the IL-1 decoy receptor (type II) in human neutrophils along with the production of the IL-1 receptor antagonist. In the present study we focused on further studying the modulatory effects of IL-13 on these cells. We found that recombinant human IL-13 (rhIL-13) induces cellular morphological changes in neutrophils that are typical of activated cells. Furthermore, rhIL-13 was shown to increase tyrosine phosphorylation of several neutrophil proteins. We also demonstrate that this cytokine stimulates de novo RNA synthesis in a concentration-dependent fashion as measured by [5-3H]uridine incorporation and that rhIL-13 induces the synthesis of several neutrophil proteins according to high-resolution two-dimensional gel electrophoresis of metabolically [35S]-labeled cells. We observed that the IL-8 levels in the external milieu of IL-13-stimulated cells was almost fivefold increased when compared with control cells. Finally, we observed that rhIL-13 has no significant effect on phagocytosis and apoptosis. Taken together, our results demonstrate that IL-13 is a modulator of several human neutrophil functions. This leads us to conclude that the modulatory role of IL-13 on human neutrophils, a potentially important anti-inflammatory cytokine, is more complex than previously believed. Furthermore, because we show that the synthesis of several as yet unidentified proteins was up-regulated by IL-13, our findings open new avenues of research on the effects of this cytokine on human neutrophils.

Epstein-Barr virus modulates de novo protein synthesis in human neutrophils

Neutrophils and macrophages represent the first line of defense against microbial invaders. However, the role of phagocytes in host response to viral infection is poorly understood. We have previously shown that Epstein-Barr virus (EBV) interacts with human monocytes and modulates cytokine production in this cell type, but its effects on neutrophils are still unknown. In the present study, we investigated the presence of EBV receptor (CR2 or CD21) on neutrophils by cytofluorometry using five different anti-CD21 monoclonal antibodies (MoAbs), as well as fluoroscein isothiocyanate-EBV (FITC-EBV). Whereas no significant amount of neutrophils reacted with anti-CD21 MoAbs, studies with FITC-EBV indicated that viral particles bind to 30% of cells (in some individuals, EBV binds to more than 50% of neutrophils). This interaction is specific as it was completely inhibited by nonconjugated virus or with labeled virus preincubated with neutralizing MoAbs. After EBV treatment, cellular aggregation was observed in neutrophil cultures, an indication that neutrophils were activated. Although EBV did not induce respiratory burst activity in neutrophils, pretreatment with infectious particles enhanced (priming effect) the fMLP-induced O2- release in neutrophils. Instead of restricting our analysis to specific cytokine genes, we investigated the effects of EBV on neutrophil transcriptional events in general. The effect of this virus on de novo synthesis of total cellular RNA was first investigated by measuring the incorporation of [5-3H] uridine into total RNA. The results showed that RNA synthesis in neutrophils was significantly increased (2.3- to 21.3-fold) by EBV compared with the unstimulated controls. Live and UV-inactivated virus markedly induced RNA synthesis, whereas heat-inactivated virus lost this ability. Induction of RNA transcription was EBV specific, as an EBV-neutralizing antiserum abolished this effect. Induction of protein synthesis was also studied by measuring the incorporation of [35S] methionine and [35S] cysteine into secreted and intracellular proteins in neutrophils incubated with EBV. The synthesis of both secreted and cytoplasmic proteins was induced by EBV. One- and two-dimensional gel electrophoresis analysis showed that EBV modulates protein synthesis, because activation of the synthesis of certain proteins was accompanied by the inhibition of others. Interleukin-1 beta (IL-1 beta) and IL-1 receptor antagonist (IL-1Ra) synthesis was found to be induced by EBV. Therefore, modulation of host-response proteins such as IL-1Ra could be one of the many mechanisms by which this virus avoids rejection.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of interleukin-2 on gene expression in human neutrophils

Recently, the interleukin-2 receptor (IL-2R) was shown to be present on human neutrophils, and IL-2-neutrophil interactions are believed to be important in both tumor rejection and increased susceptibility to bacterial infections. Furthermore, neutrophils have been shown to synthesize host defense proteins, such as cytokines. In this study, we analyzed the effects of IL-2 on the induction of de novo RNA and protein synthesis in this cell type. When cells were stimulated with IL-2 alone, the level of incorporation of either [5-3H]-uridine or [35S]-methionine and [35S]-cysteine was similar to unstimulated cells. However, when cells were stimulated with the combination of a fixed concentration of granulocyte-macrophage colony-stimulating factor (GM-CSF), a dose-dependent effect of IL-2 was observed on the induction of both RNA and protein synthesis. In the presence of tumor necrosis factor-alpha or formyl-methionyl-leucyl-phenylalanine, however, IL-2 exerted no similar effect. Furthermore, the study of a large number of normal subjects (n = 55) showed reproducible categories of responders (low, intermediate, and high). The binding of IL-2 to the IL-2R complex on human neutrophils increased on GM-CSF-stimulated neutrophils compared with unstimulated cells. However, no increase in the level of expression of either the alpha or beta chains of this receptor complex was observed. This finding suggests that GM-CSF functionally activates the IL-2R, but does not regulate its level of expression. Finally, we found that human neutrophils constitutively express IL-2R gamma chain mRNA and thus have the potential to express the functional IL-2R complex. Our findings on IL-2-neutrophil interactions should lead to new avenues of research in understanding the responses of patients undergoing GM-CSF or IL-2 therapy.

Differential effects of high fat diets on fatty acid composition in milk of Jersey and Holstein cows

Effects of increasing dietary intake of calcium salts of palm fatty acid distillate (0, .25, .50, and .75 kg/d) on milk yield and milk fat composition were investigated for Jersey and Holstein cows. Increased dietary fat decreased DMI but did not influence milk yield or fat and protein contents. Jersey milk fat contained a higher proportion of short- and medium-chain fatty acids and lower proportions of palmitic and oleic fatty acids than did Holstein milk fat. With few exceptions, increased dietary fat altered the proportions of milk fatty acids in a parallel manner in both breeds. Except for butyrate, for which an effect was inconsistent, and palmitate, which was increased, additional dietary fat inhibited de novo synthesis of the milk fatty acids. The inhibition increased as the chain length of the fatty acids increased. Additional dietary fat increased the ratio of C18:1:C18:0 in Holstein cows, but the ratio was unchanged by dietary fat in Jersey cows. The regulation of fluidity of milk fat may differ between the two breeds.

Differential expression of two major cytokines produced by neutrophils, interleukin-8 and the interleukin-1 receptor antagonist, in neutrophils isolated from the synovial fluid and peripheral blood of patients with rheumatoid arthritis

OBJECTIVE

Neutrophils have been shown to produce interleukin-8 (IL-8) and interleukin-1 receptor antagonist (IL-1ra) in large amounts compared with other cytokines. Since IL-8 has a proinflammatory action whereas IL-1ra is antiinflammatory, our objective was to examine the relative levels of production of these cytokines by synovial fluid (SF) neutrophils isolated from patients with rheumatoid arthritis (RA).

METHODS

We measured cytokine production using an enzyme-linked immunosorbent assay and analyzed messenger RNA accumulation in cells by Northern blot.

RESULTS

SF neutrophils produced significantly more IL-8 and IL-1 beta, but significantly less IL-1ra, than peripheral blood neutrophils.

CONCLUSION

These observations provide new information on the production of pro- and antiinflammatory molecules by neutrophils in the SF environment, and their possible role in RA.

Feed and animal factors influencing milk fat composition

Genetic selection for increased milk fat percentage leads to increased proportions of short-chain fatty acids in milk fat and decreased proportions of long-chain fatty acids. Milk fat composition is strongly influenced by stage of lactation; proportion of short chains (de novo synthesis) is low initially and increases until at least 8 to 10 wk into lactation. Milk fat composition is changed more by the amount and composition of dietary fat than any other dietary component. Seasonal and regional differences in milk fat composition are measurable, most likely because of local differences in feed supplies. Milk fat composition can be modified readily by changing the feeding regimen. The most significant changes in milk fat quality relate to rheological (melting) properties, which influence numerous aspects of character and quality of manufactured dairy products. Dietary fat fed to change milk fat composition may also influence contents of protein, urea, citrate, and soluble calcium in milk and influence oxidative stability and flavor. It is important for both dairy nutritionists and dairy food chemists to understand the consequences of feeding programs on milk quality.

Human neutrophils produce high levels of the interleukin 1 receptor antagonist in response to granulocyte/macrophage colony-stimulating factor and tumor necrosis factor alpha

Neutrophils, an abundant cell type at sites of inflammation, have the ability to produce a number of cytokines, including interleukin 1 (IL-1), IL-8, granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor alpha (TNF-alpha). In this study, we have examined the ability of human neutrophils to produce the IL-1 receptor antagonist (IL-1Ra), a 17-23-kD protein recently isolated and cloned from macrophages. Since IL-1Ra has been shown to inhibit both the in vitro and in vivo effects of IL-1, its production by large numbers of tissue-invading neutrophils might provide a mechanism by which the effects of IL-1 are regulated in inflammation. Using antibodies that are specific for IL-1Ra and a cDNA probe encoding for this protein, we were able to show that neutrophils constitutively produce IL-1Ra. However, after activation by GM-CSF and TNF-alpha, IL-1Ra was secreted into the extracellular milieu where it constituted the major de novo synthesized product of activated neutrophils. None of a large array of other potent neutrophil agonists were found to affect the production of IL-1Ra by neutrophils. Quantitative measurements by enzyme-linked immunosorbent assay revealed that intracellular IL-1Ra is in eightfold excess of the amount secreted in supernatants when studying nonactivated neutrophils. However, in GM-CSF- and TNF-alpha-activated cells, this difference was reduced to values between four- and fivefold, as virtually all of the de novo synthesized IL-1Ra was secreted. In activated cells, the intracellular content of IL-1Ra was found to be in the 2-2.5-ng/ml range per 10(6) neutrophils, whereas levels reached the 0.5-ng/ml range in supernatants. This would imply that IL-1Ra is produced in excess of IL-1 by a factor of at least 100, an observation that is in agreement with the reported amounts of IL-1Ra needed to inhibit the proinflammatory effects of IL-1. Neutrophils isolated from an inflammatory milieu, the synovial fluid of patients with rheumatoid arthritis, were found to respond to GM-CSF and TNF-alpha in terms of IL-1Ra synthesis, indicating that the in vitro observations made in this study are likely to occur in an inflammatory setting in vivo.

Nuclear signaling in human neutrophils. Stimulation of RNA synthesis is a response to a limited number of proinflammatory agonists

At inflammatory sites, neutrophils are stimulated by a range of proinflammatory molecules which elicit a number of cellular responses. Considerable information on the cytoplasmic events that occur following activation of neutrophils at the cell membrane level already exists. In this study, we have focused on the ability of neutrophil agonists to initiate nuclear signaling events by investigating the induction of de novo RNA synthesis. Of a total of 14 different known potent leukocyte agonists, only three had a significant effect on the induction of RNA synthesis in neutrophils; the formylated oligopeptide formyl-methionyl-leucylphenylalanine (fMet-Leu-Phe), granulocyte-macrophage colony-stimulating factor, and tumor necrosis factor alpha. All three agonists induced de novo RNA synthesis in neutrophils at concentrations known to be optimal for the activation of a number of other cellular responses occurring in inflammation. Of significance was the observation that activation of RNA synthesis in neutrophils is a G-protein-mediated event, is also dependent on tyrosine phosphorylation, but is not influenced by cAMP. Finally, we have demonstrated that all three agonists also induce de novo synthesis of a limited number of proteins, with granulocyte-macrophage colony-stimulating factor and fMet-Leu-Phe having the most potent effect. These studies define the effects of neutrophil agonists on de novo RNA and protein synthesis in a proinflammatory context and suggest that these events in neutrophils occur in a restricted fashion, highly dependent on the stimuli present at sites of inflammation.

Differential synthesis of 5-lipoxygenase in peripheral blood and synovial fluid neutrophils in rheumatoid arthritis

In order to investigate 5-lipoxygenase enzyme regulation in neutrophils during an inflammatory reaction, we studied 5-lipoxygenase mRNA levels, as well as de novo enzyme synthesis, in resting and activated neutrophils isolated from normal individuals and patients with rheumatoid arthritis. The approach used was to analyze these activities in resting peripheral blood neutrophils of normal individuals on the one hand and in peripheral blood and matched synovial fluid neutrophils isolated from patients with rheumatoid arthritis on the other hand. Our first observation was that resting peripheral blood neutrophils of either normal individuals or patients show detectable levels of 5-lipoxygenase mRNA and are able to synthesize the enzyme de novo. Our second observation was that inflammatory activated neutrophils from synovial fluid reveal lower 5-lipoxygenase mRNA levels and enzyme synthesis than do the patient-matched peripheral blood cells. This is in spite of the fact that, for other proteins, synovial fluid neutrophils are equally or more active than their peripheral blood counterparts. We conclude that peripheral blood neutrophils are capable of synthesizing the enzyme, thus ensuring the turnover of the protein. Furthermore, complex regulatory mechanisms appear to take place in response to inflammation as it occurs in synovial fluids of patients with rheumatoid arthritis, leading to decreased mRNA levels and enzyme synthesis. Possible mechanisms of regulation are discussed and are presently under investigation.

Differential synthesis of 5-lipoxygenase in peripheral blood and synovial fluid neutrophils in rheumatoid arthritis

In order to investigate 5-lipoxygenase enzyme regulation in neutrophils during an inflammatory reaction, we studied 5-lipoxygenase mRNA levels, as well as de novo enzyme synthesis, in resting and activated neutrophils isolated from normal individuals and patients with rheumatoid arthritis. The approach used was to analyze these activities in resting peripheral blood neutrophils of normal individuals on the one hand and in peripheral blood and matched synovial fluid neutrophils isolated from patients with rheumatoid arthritis on the other hand. Our first observation was that resting peripheral blood neutrophils of either normal individuals or patients show detectable levels of 5-lipoxygenase mRNA and are able to synthesize the enzyme de novo. Our second observation was that inflammatory activated neutrophils from synovial fluid reveal lower 5-lipoxygenase mRNA levels and enzyme synthesis than do the patient-matched peripheral blood cells. This is in spite of the fact that, for other proteins, synovial fluid neutrophils are equally or more active than their peripheral blood counterparts. We conclude that peripheral blood neutrophils are capable of synthesizing the enzyme, thus ensuring the turnover of the protein. Furthermore, complex regulatory mechanisms appear to take place in response to inflammation as it occurs in synovial fluids of patients with rheumatoid arthritis, leading to decreased mRNA levels and enzyme synthesis. Possible mechanisms of regulation are discussed and are presently under investigation.

Selective synthesis and secretion of a 23 kD protein by neutrophils following stimulation with granulocyte-macrophage colony-stimulating factor and tumor necrosis factor-alpha

We tested a wide range of pro-inflammatory cytokines for their capacity to activate protein synthesis in neutrophils as analyzed b y [35S] methionine metabolic labelling experiments. Of all the cytokines tested, only GM-CSF and TNF alpha stimulated significant synthesis and secretion of a 23 kD protein which resolved into two bands on two dimensional gels. Under non-reducing conditions on one dimensional gels, its migration pattern remained the same indicating that the two bands most likely represent isoforms of the same protein. Immunoisolation studies using antibodies directed against size-relevant molecules did not lead to the identification of this molecule. The fact that this 23 kD molecule is induced in a highly specific and selective manner by GM-CSF and TNF alpha indicates that it may play a key role in some of the responses of neutrophils to these two cytokines. Therefore, full characterization of this 23 kD protein could provide important new knowledge on the mechanisms by which these two cytokines exert their biological effects on neutrophils.

Thrombospondin and fibronectin are synthesized by neutrophils in human inflammatory joint disease and in a rabbit model of in vivo neutrophil activation

Using 35S-methionine metabolic labeling, we studied de novo synthesis and secretion of proteins by activated polymorphonuclear neutrophils (PMN) from two different sources. PMN isolated from inflammatory synovial fluid of patients with inflammatory joint disease were first analyzed. The protein synthetic activity of these cells was compared with that of nonactivated PMN isolated from the peripheral blood of the same patient. Similar studies were conducted on glycogen-activated PMN from the peritoneal cavity of rabbits and results were compared with nonactivated peripheral blood PMN isolated from the same rabbit. Cells were labeled for a period of 16 to 20 h and supernatants were analyzed by one and two dimensional gel electrophoresis. In both models, the activated PMN showed a marked increase in the synthesis and secretion of thrombospondin as identified by immunoisolation with antibodies to this protein. The production of thrombospondin by activated cells paralleled a similar increase in production of another extracellular matrix and cell adhesion protein, fibronectin. The proportion of thrombospondin synthesis and secretion relative to total protein was approximately 1% in both human- and rabbit-activated PMN. For fibronectin, this proportion was in the 0.02% range. Although fibronectin mRNA accumulation in activated PMN could be demonstrated by Northern blots, we were not able to obtain similar results for thrombospondin mRNA. This could be caused by the rapid turnover of this transcript because it is known to contain an adenine uridine-rich 3' untranslated sequence. We conclude that activated PMN are capable of producing thrombospondin. Furthermore, glycogen-activated rabbit peritoneal fluid PMN represent a valuable and relevant source of activated PMN for studying the protein synthetic events of these cells in the context of inflammation.

Thrombospondin and fibronectin are synthesized by neutrophils in human inflammatory joint disease and in a rabbit model of in vivo neutrophil activation

Using 35S-methionine metabolic labeling, we studied de novo synthesis and secretion of proteins by activated polymorphonuclear neutrophils (PMN) from two different sources. PMN isolated from inflammatory synovial fluid of patients with inflammatory joint disease were first analyzed. The protein synthetic activity of these cells was compared with that of nonactivated PMN isolated from the peripheral blood of the same patient. Similar studies were conducted on glycogen-activated PMN from the peritoneal cavity of rabbits and results were compared with nonactivated peripheral blood PMN isolated from the same rabbit. Cells were labeled for a period of 16 to 20 h and supernatants were analyzed by one and two dimensional gel electrophoresis. In both models, the activated PMN showed a marked increase in the synthesis and secretion of thrombospondin as identified by immunoisolation with antibodies to this protein. The production of thrombospondin by activated cells paralleled a similar increase in production of another extracellular matrix and cell adhesion protein, fibronectin. The proportion of thrombospondin synthesis and secretion relative to total protein was approximately 1% in both human- and rabbit-activated PMN. For fibronectin, this proportion was in the 0.02% range. Although fibronectin mRNA accumulation in activated PMN could be demonstrated by Northern blots, we were not able to obtain similar results for thrombospondin mRNA. This could be caused by the rapid turnover of this transcript because it is known to contain an adenine uridine-rich 3' untranslated sequence. We conclude that activated PMN are capable of producing thrombospondin. Furthermore, glycogen-activated rabbit peritoneal fluid PMN represent a valuable and relevant source of activated PMN for studying the protein synthetic events of these cells in the context of inflammation.