Effects of Fatty Acid Supplements on Milk Yield and Energy Balance of Lactating Dairy Cows

Saturated and unsaturated fatty acid supplements (FS) were evaluated for effects on yield of milk and milk components, concentration of milk components including milk fatty acid profile, and energy balance. Eight ruminally and duodenally cannulated cows and 8 noncannulated cows were used in a replicated 4 x 4 Latin square design experiment with 21-d periods. Treatments were control and a linear substitution of 2.5% fatty acids from saturated FS (SAT; prilled, hydrogenated free fatty acids) for partially unsaturated FS (UNS; calcium soaps of long-chain fatty acids). The SAT treatment did not change milk fat concentration, but UNS linearly decreased milk fat in cannulated cows and tended to decrease milk fat in noncannulated cows compared with control. Milk fat depression with UNS corresponded to increased concentrations of trans-10, cis-12 conjugated linoleic acid and trans C18:1 fatty acids in milk. Milk fat profile was similar for SAT and control, but UNS decreased concentration of short- and medium-chain FA. Digestible energy intake tended to decrease linearly with increasing unsaturated FS in cannulated and noncannulated cows. Increasing unsaturated FS linearly increased empty body weight and net energy gain in cannulated cows, whereas increasing saturated FS linearly increased plasma insulin. Efficiency of conversion of digestible energy to milk tended to decrease linearly with increasing unsaturated FS for cannulated cows only. Addition of SAT provided little benefit to production and energy balance, whereas UNS decreased energy intake and milk energy yield.

Effects of Fatty Acid Supplements on Ruminal and Total Tract Nutrient Digestion in Lactating Dairy Cows

Saturated and unsaturated fatty acid supplements (FS) were evaluated for effects on ruminal digestion kinetics, and ruminal and postruminal nutrient digestion. Eight early lactation ruminally and duodenally cannulated cows (77 +/- 12 days in milk, mean +/- SD) were used in a replicated 4 x 4 Latin square design experiment with 21-d periods. Treatments were control and a linear substitution of 2.5% fatty acids from supplemented saturated FS (SAT; prilled, hydrogenated free fatty acids) for partially unsaturated FS (UNS; calcium soaps of long-chain fatty acids). All rations contained identical forage and concentrate components including 37.2% forage and 13.5% cottonseed. Saturated FS linearly decreased ruminal digestibility of dry matter and organic matter and linearly decreased ruminal neutral detergent fiber (NDF) digestibility. The reduction in ruminal NDF digestibility was because of a linear decrease in digestion rate and a linear increase in passage rate of potentially digestible NDF with increasing saturated FS. Total tract digestibility of NDF was not different between treatments because of compensatory postruminal digestion. Ruminal fatty acid and C18 fatty acid digestibility tended to increase linearly with increasing unsaturated FS, and postruminal C18 fatty acid digestibility decreased with increasing saturated FS. Saturated FS linearly decreased ruminal organic matter digestibility and decreased intestinal long-chain fatty acid digestibility, although differences in fatty acid digestibility may be partially explained by fatty acid intake.

Gene network shaping of inherent noise spectra

Recent work demonstrates that stochastic fluctuations in molecular populations have consequences for gene regulation. Previous experiments focused on noise sources or noise propagation through gene networks by measuring noise magnitudes. However, in theoretical analysis, we showed that noise frequency content is determined by the underlying gene circuits, leading to a mapping between gene circuit structure and the noise frequency range. An intriguing prediction from our previous studies was that negative autoregulation shifts noise to higher frequencies where it is more easily filtered out by gene networks--a property that may contribute to the prevalence of autoregulation motifs (for example, found in the regulation of approximately 40% of Escherichia coli genes). Here we measure noise frequency content in growing cultures of E. coli, and verify the link between gene circuit structure and noise spectra by demonstrating the negative autoregulation-mediated spectral shift. We further demonstrate that noise spectral measurements provide mechanistic insights into gene regulation, as perturbations of gene circuit parameters are discernible in the measured noise frequency ranges. These results suggest that noise spectral measurements could facilitate the discovery of novel regulatory relationships.

The Effect of Production Level on Feed Intake, Milk Yield, and Endocrine Responses to Two Fatty Acid Supplements in Lactating Cows

Animal responses to dietary treatment may interact with metabolic state, which differs for cows across a wide range of milk yield. Responses to dietary saturated vs. unsaturated fatty acid (FA) supplement was evaluated using 32 multiparous Holstein cows arranged in a crossover design with 14-d periods. Treatments were 2.5% FA from unsaturated FA (calcium salts of palm FA) or saturated FA (prilled, hydrogenated free FA). Unsaturated FA treatments decreased dry matter intake (0.8 kg/d) and time spent ruminating (25 min/d) compared with saturated FA treatment. Treatments did not differ in milk or 3.5% fat-corrected milk yield. Intake and milk yield responses were not related to milk yield across cows. Saturated FA treatment increased milk protein and lactose concentrations, but treatment did not affect yield of milk components. Saturated FA treatment increased insulin over 25% and decreased nonesterified FA nearly 20% with no effect on plasma somatotropin, glucose, or beta-hydroxybutyrate concentrations. Milk protein concentration and yield responses to treatment were positively correlated with pretrial fat-corrected milk yield. Milk protein response was not related to insulin response, supporting the importance of insulin sensitivity in control of milk protein synthesis. Unsaturated FA treatment decreased dry matter intake and rumination time compared with saturated FA treatment, consistent with reports of unsaturated fat increasing satiety and decreasing gut motility. Decreased milk protein synthesis by fat supplementation may be related to FA saturation and milk yield of cows.

Effectiveness of Screening Aqueous Contrast Swallow in Detecting Clinically Significant Anastomotic Leaks after Esophagectomy

BACKGROUND

Aqueous contrast swallow study is recommended as a screening procedure for the evaluation of esophageal anastomotic integrity following esophagectomy. The aim of this study was to assess the accuracy of water-soluble contrast swallow screening as a predictor of clinically significant anastomotic leak in patients with esophagectomy.

PATIENTS AND METHODS

The records of 505 consecutive patients undergoing esophagectomy in Mayo Clinic from January 1991 through December 1995 were retrospectively reviewed. 464 (92%) patients had water-soluble contrast swallows performed in the early postoperative period (median postoperative day 7, range 4-11 days).

RESULTS

A total of 39 radiological leaks were obtained but only 17 of these had clinical signs of anastomotic leakage. Furthermore, 25 patients who had normal swallow study developed a clinical anastomotic leak. There were therefore 22 (4.7%) false positive and 25 (5.4%) false negative results giving values for the specificity, sensitivity and false negative error rate of the radiological examination of 94.7, 40.4, and 59.5% respectively. Aspiration of the contrast agent was noted on fluoroscopy in 30 (6.5%) patients. Only 2 (0.4%) patients developed aqueous contrast agent-caused aspiration pneumonia. There was no procedure-related mortality.

CONCLUSION

While radiological assessment of esophageal anastomoses in the early postoperative period using aqueous contrast agents appears to be a relatively safe procedure, the poor sensitivity and high false negative error rate of this technique, when performed on postoperative day 7 and in a series with clinical anastomotic leak rate of 9%, is insufficient for it to be worthwhile as a screening procedure.

Corn Grain Endosperm Type and Brown Midrib 3 Corn Silage: Site of Digestion and Ruminal Digestion Kinetics in Lactating Cows

Interactions of endosperm type of corn grain and the brown midrib 3 (bm3) mutation in corn silage on ruminal kinetics and site of nutrient digestion of lactating dairy cows were evaluated. Eight ruminally and duodenally cannulated cows (72 +/- 8 d in milk; mean +/- SD) were used in a duplicated 4 x 4 Latin square design experiment with a 2 x 2 factorial arrangement of treatments. Treatments were corn grain endosperm type (floury or vitreous) and corn silage type (bm3 or isogenic normal). Diets contained 26% neutral detergent fiber (NDF) and 30% starch. Interactions of treatments were not observed for any measure of digestibility, but digestion kinetics of starch and fiber did interact to affect digestible organic matter intake by affecting dry matter intake. Rate of ruminal starch digestion was faster and rate of ruminal starch passage tended to be slower in diets containing corn grain with floury vs. vitreous endosperm, resulting in a mean increase of 22 units for ruminal starch digestibility. Although compensatory postruminal starch digestion decreased differences among treatments for total tract starch digestibility, starch entering the duodenum was more digestible for grain with floury endosperm compared with vitreous grain, resulting in greater total tract starch digestibility for floury compared with vitreous corn grain. Fermentation rate of potentially digestible NDF was not affected by either bm3 corn silage or greater ruminal starch digestion of floury grain. Brown midrib corn silage increased total tract NDF digestibility vs. control silage by numerically increasing ruminal and postruminal digestibility of NDF. Endosperm type of corn grain greatly influences site of starch digestion and should be considered when formulating diets.

Corn Grain Endosperm Type and Brown Midrib 3 Corn Silage: Feeding Behavior and Milk Yield of Lactating Cows

Interactions of endosperm type of corn grain and the brown midrib 3 mutation (bm3) in corn silage on feeding behavior, productivity, energy balance, and plasma metabolites of lactating dairy cows were evaluated. Eight ruminally and duodenally cannulated cows (72 +/- 8 d in milk; mean +/- SD) were used in a duplicated 4 x 4 Latin square design experiment with a 2 x 2 factorial arrangement of treatments. Treatments were corn grain endosperm type (floury or vitreous), and corn silage type (bm3 or isogenic control). Diets contained 26% neutral detergent fiber (NDF) and 30% starch. Floury endosperm grain decreased dry matter intake (DMI) 1.9 kg/ d compared with vitreous grain when combined with control corn silage but did not affect DMI when combined with bm3 corn silage. This interaction of treatments occurred because of changes in meal size; floury endosperm grain decreased meal size in control silage diets but increased meal size in bm3 corn silage diets. Ruminal pool sizes reflected DMI differences among diets, suggesting that ruminal fill was not the primary limitation on intake. Brown midrib 3 corn silage reduced rumination time per day and number of rumination bouts per day. Floury endosperm grain decreased 3.5% fat-corrected milk by 1.2 kg/d when combined with control silage but increased 3.5% fat-corrected milk by 2.1 kg/d when combined with bm3 corn silage. Starch and fiber digestibility interact to affect feeding behavior and milk production and production response to bm3 corn silage depends on the grain source that is fed.

Corn Grain Endosperm Type and Brown Midrib 3 Corn Silage: Ruminal Fermentation and N Partitioning in Lactating Cows

Interactions of endosperm type of corn grain and the brown midrib 3 mutation (bm3) in corn silage on ruminal fermentation and microbial efficiency of lactating dairy cows were evaluated. Eight ruminally and duodenally cannulated cows (72 +/- 8 d in milk; mean +/- SD) were used in a duplicated 4 x 4 Latin square design experiment with a 2 x 2 factorial arrangement of treatments. Treatments were corn grain endosperm type (floury or vitreous) and corn silage type (bm3 or isogenic normal). Diets contained 26% neutral detergent fiber and 30% starch. Increasing ruminal starch digestibility by replacing vitreous corn grain with floury grain reduced mean and minimum ruminal pH. Brown midrib 3 corn silage reduced mean and minimum ruminal pH and increased total volatile fatty acid concentration. Ruminal pH was positively associated with rate of valerate absorption. Although floury endosperm reduced acetate:propionate ratio in both control and bm3 corn silage diets, it had a greater effect on reducing acetate:propionate ratio for control silage compared with bm3 corn silage. Nonammonia N flow to the duodenum did not differ among treatments and no effects of treatment were detected for microbial N and nonammonia, nonmicrobial N flow. Although treatment effects on ruminal fermentation and ruminal pH were observed, few interactions of treatment were detected and treatments did not affect flow of N fractions to the intestines.

Milk Fat Responses to a Change in Diet Fermentability Vary by Production Level in Dairy Cattle

The effects of dietary starch fermentability on plasma metabolites and hormones, milk production, and milk fatty acid profile were evaluated in a crossover study. Thirty-two multiparous Holstein cows (121 +/- 48 d in milk, 41 +/- 9 kg/d 3.5% fat-corrected milk [FCM]; mean +/- SD) were randomly assigned to treatment sequence and were fed a diet intermediate to the treatments during an initial 21-d period. Treatments were dry ground corn grain (DG) and high moisture corn (HM) harvested from the same field. Treatment periods were 14 d, with the final 4 d used for data and sample collection. Diets included corn silage and alfalfa haylage at a 2:1 ratio and were ~26% neutral detergent fiber, 16.5% crude protein, 32% starch, and 3.5% fatty acids. High moisture corn increased plasma glucose, nonesterified fatty acid, and triglyceride concentrations, but treatment had no consistent effect on yield of milk or FCM. High moisture corn increased trans C(18:1) concentrations at an increasing rate as production level decreased across cows, and milk fat depression was evident in cows below approximately 40 kg/d FCM yield. In contrast, production level had little influence on milk trans C(18:1) concentration for DG. Milk trans C(18:1) concentration was negatively correlated with milk fat concentration, as was trans-9 C(18:1), trans-10 C(18:1), and cis-9, trans-11 C(18:2). Concentration of trans-10, cis-12 C(18:2) was not correlated with milk fat concentration. Production level may influence biohydrogenation patterns and trans C(18:1) production because of differences in rumen environment; rumen pH and dilution rate can alter metabolism and populations of rumen microbes. Diets with highly fermentable starch sources and without supplemental dietary polyunsaturated fatty acids can induce milk fat depression in lower-producing cows, likely because of increased production of trans C(18:1) fatty acids.

Pelleted Beet Pulp Substituted for High-Moisture Corn: 2. Effects on Digestion and Ruminal Digestion Kinetics in Lactating Dairy Cows

The effects of increasing concentrations of dried, pelleted beet pulp substituted for high-moisture corn on digestion and ruminal digestion kinetics were evaluated using eight ruminally and duodenally cannulated multiparous Holstein cows in a duplicated 4 x 4 Latin square design with 21-d periods. Cows were 79 +/- 17 (mean +/- SD) d in milk at the beginning of the experiment. Experimental diets with 40% forage (corn silage and alfalfa silage) and 60% concentrate contained 0, 6.1, 12.1, or 24.3% beet pulp substituted for high-moisture corn on a dry matter basis. Diet concentrations of neutral detergent fiber (NDF) and starch were 24.3 and 34.6% (0% beet pulp), 26.2 and 30.5% (6% beet pulp), 28.0 and 26.5% (12% beet pulp), and 31.6 and 18.4% (24% beet pulp), respectively. Ruminal dry matter pool decreased and NDF turnover rate increased as dietary beet pulp content increased. Potentially digestible NDF was digested more extensively and at a faster rate in the rumen with increasing beet pulp, resulting in increased total tract NDF digestibility. Passage rates of potentially digestible NDF and of indigestible NDF were not affected by treatment. True ruminal digestibility of starch decreased with increasing beet pulp substitution. This was caused by a linear increase in starch passage rate, possibly because of increasing ruminal fill, and a linear decrease in digestion rate of starch in the rumen, possibly because of reduced amylolytic enzyme activity for lower-starch diets. Although true ruminal starch digestibility decreased when more beet pulp was fed, whole tract starch digestibility was not affected because of compensatory digestion of starch in the intestines. Due to more thorough digestion of fiber in diets containing more beet pulp, whole-tract digestibility of organic matter increased linearly, and intake of digestible organic matter was not affected. Partially replacing high-moisture corn with beet pulp in low-forage diets increased fiber digestibility without reducing whole-tract starch digestibility.

Pelleted Beet Pulp Substituted for High-Moisture Corn: 1. Effects on Feed Intake, Chewing Behavior, and Milk Production of Lactating Dairy Cows

The effects of increasing concentrations of dried, pelleted beet pulp substituted for high-moisture corn on intake, milk production, and chewing behavior were evaluated using eight ruminally and duodenally cannulated multiparous Holstein cows in a duplicated 4 x 4 Latin square design with 21-d periods. Cows were 79 +/- 17 (mean +/- SD) d in milk at the beginning of the experiment. Experimental diets with 40% forage (corn silage and alfalfa silage) and 60% concentrate contained 0, 6.1, 12.1, or 24.3% beet pulp substituted for high-moisture corn on a dry matter basis. Diet concentrations of neutral detergent fiber (NDF) and starch were 24.3 and 34.6% (0% beet pulp), 26.2 and 30.5% (6% beet pulp), 28.0 and 26.5% (12% beet pulp), and 31.6 and 18.4% (24% beet pulp), respectively. Increasing beet pulp in the diet caused a linear decrease in dry matter intake (DMI). Time spent eating per day and per kilogram of DMI increased, and sorting against NDF tended to increase, with added beet pulp. Substituting beet pulp for corn caused a quadratic response in milk fat yield, with the highest yield for the 6% beet pulp treatment. A tendency was detected for a similar quadratic response in 3.5% fat-corrected milk yield. Lower plasma insulin concentration may have resulted in lower body condition gain for cows fed diets with higher beet pulp concentration. Partial substitution of pelleted beet pulp for high-moisture corn decreased intake but also may have permitted greater fat-corrected milk yield.

Pelleted Beet Pulp Substituted for High-Moisture Corn: 3. Effects on Ruminal Fermentation, pH, and Microbial Protein Efficiency in Lactating Dairy Cows

The effects of increasing concentrations of dried, pelleted beet pulp substituted for high-moisture corn on ruminal fermentation, pH, and microbial efficiency were evaluated using eight ruminally and duodenally cannulated multiparous Holstein cows in a duplicated 4 x 4 Latin square design with 21-d periods. Cows were 79 +/- 17 (mean +/- SD) DIM at the beginning of the experiment. Experimental diets with 40% forage (corn silage and alfalfa silage) and 60% concentrate contained 0, 6.1, 12.1, or 24.3% beet pulp substituted for high-moisture corn on a DM basis. Diet concentrations of NDF and starch were 24.3 and 34.6% (0% beet pulp), 26.2 and 30.5% (6% beet pulp), 28.0, and 26.5% (12% beet pulp), and 31.6 and 18.4% (24% beet pulp), respectively. Substituting beet pulp for corn did not affect daily mean or minimum ruminal pH but tended to reduce pH range. Ruminal acetate:propionate responded in a positive exponential relationship to added beet pulp. Rate of valerate absorption from the rumen was not affected by treatment. Substituting beet pulp for corn up to 24% of diet DM did not affect efficiency of ruminal microbial protein production, expressed as microbial N flow to the duodenum as a percentage of OM truly digested in the rumen. Microbial efficiency was not correlated to mean pH or daily minimum pH. While microbial efficiency was not directly related to concentration of beet pulp fed, it was positively correlated with passage rate of particulate matter, as represented by starch and indigestible NDF, probably due to reduced turnover of microbial protein in the rumen.

Dose-Response Effects of Intrauminal Infusion of Propionate on Feeding Behavior of Lactating Cows in Early or Midlactation

The objective of this experiment was to evaluate whether dose-response effects of intraruminal infusion of propionate on feeding behavior and dry matter intake (DMI) differ by stage of lactation. Six cows in early lactation (EL) and six cows in midlactation (ML) were assigned to blocks in a duplicated 6 x 6 Latin square design experiment. Treatments were mixtures of sodium propionate and sodium acetate containing sodium propionate at 0, 20, 40, 60, 80, and 100% of total volatile fatty acids (VFA), infused into the rumen continuously for 18 h starting 6 h before feeding at a rate of 21.7 mmol of sodium VFA/min. All cows were ruminally cannulated prior to the experiment. The diet was formulated to contain 30% NDF, and dry cracked corn was the major source of starch. We hypothesized that hypophagic effects of propionate infusion were greater for EL compared with ML because of greater plasma concentration of nonesterified fatty acids (275 vs. 76 microMeq/L) and expected greater basal oxidative metabolism in the liver for EL compared to ML. Propionate infusion decreased DMI for EL and ML, but a quadratic effect of propionate infusion was observed for ML but not EL. This indicated a greater marginal reduction in DMI at higher doses of propionate for ML compared to EL, contrary to our hypothesis. Propionate infusion decreased meal size similarly for both stages of lactation, but linearly increased intermeal interval for ML but not EL. We speculate that lower milk yield for ML compared with EL (30.8 vs. 42.0 kg/d) decreased glucose demand by the mammary gland and increased the proportion of infused propionate oxidized in the liver for ML compared to EL.

Effects of intraruminal infusion of sodium, potassium, and ammonium on hypophagia from propionate in lactating dairy cows

The objective of this experiment was to evaluate effects of salt type on hypophagic effects of intraruminal infusion of propionate in lactating dairy cows. Our working hypothesis is that oxidative metabolism of propionate causes satiety by increasing hepatic ATP concentration and decreasing the discharge rate of the hepatic vagus. We hypothesized that hypophagic effects of propionate are reduced by ammonium and potassium. We speculated that ammonium infusion lowers hepatic ATP concentration because ATP is used for urea synthesis and potassium increases the discharge rate of the hepatic vagus. Eight ruminally cannulated Holstein cows in midlactation were used in a duplicated 4 x 4 Latin square design experiment. Treatments were intraruminal infusion of propionic acid, ammonium propionate, sodium propionate, and potassium propionate. Treatment solutions were 0.93 M for propionate and 0.67 M for salts among the treatments except for propionic acid. Treatment solutions were infused over 14 h starting 2 h before feeding at 17.9 ml/min, which is equivalent to 16.7 and 11.9 mmol/min for propionate and salts, respectively. Infusion of ammonium propionate decreased dry matter intake compared with sodium propionate and potassium propionate (P < 0.04; 11.0 vs. 14.0 and 13.9 kg/12 h) by decreasing meal frequency without affecting meal size, indicating that ammonium delayed the sense of hunger. No difference in DMI and feeding behavior was observed between infusion of sodium and potassium propionate. Contrary to the hypothesis, ammonium infusion did not reduce hypophagic effects of propionate, possibly because the urea cycle indirectly stimulated oxidative metabolism in the liver by generating oxidizable carbon from amino acid catabolism.

Effects of diet fermentability on efficiency of microbial nitrogen production in lactating dairy cows

Effect of diet fermentability on efficiency of microbial N production was evaluated. Eight ruminally and duodenally cannulated Holstein cows (55 +/- 15.9 days in milk; mean +/- SD) were used in a duplicated 4 x 4 Latin square design with a 2 x 2 factorial arrangement of treatments. Experimental diets contained either ground high moisture corn (HM) or dry ground corn (DG) at two dietary starch concentrations (32 vs. 21%). All diets were formulated for 18% CP, and the sources of dietary protein were alfalfa silage (50% of forage at DM basis), soybean meal, distillers grain, and blood meal. The amount of OM truly fermented in the rumen varied from 7.7 (DG at 21% dietary starch) to 11.3 kg/d (HM at 32% dietary starch) among treatments, and was greater for high starch diets and HM treatments compared with low starch diets and DG treatments, respectively. Microbial N flow was greater for high starch diets compared with low starch diets, but was not affected by corn grain treatment. Microbial efficiency was lower for HM compared with DG treatment (39.7 vs. 48.4 g of microbial N/kg of true ruminally degraded OM), but was not affected by dietary starch concentration. Microbial efficiency was positively correlated with rate of passage for OM and starch (r = 0.77 and 0.75, respectively). Rapid passage rate may have decreased microbial turnover in the rumen, enhancing microbial efficiency. Microbial efficiency was negatively correlated with rate of starch digestion (r = -0.55), consistent with the energy spilling theory. However, energy spilling did not appear to be from lack of ammonia or low ruminal pH. Microbial efficiency was not related to ruminal ammonia concentration, daily mean ruminal pH, or minimum ruminal pH. Rate of starch availability and rates of passage for starch and OM from the rumen are important determinants of efficiency of microbial protein synthesis in vivo.

Effects of corn grain conservation method on feeding behavior and productivity of lactating dairy cows at two dietary starch concentrations

Effects of conservation method of corn grain and dietary starch concentration on dry matter intake (DMI) and productivity of lactating dairy cows were evaluated. Eight ruminally and duodenally cannulated Holstein cows (55 +/- 15.9 d in milk; mean +/- SD) were used in a duplicated 4 x 4 Latin square design with a 2 x 2 factorial arrangement of treatments. Experimental diets contained either ground high-moisture corn (HM) or dry ground corn (DG) at two dietary starch concentrations (32 vs 21%). Mean particle size and dry matter (DM) concentration of corn grain were 1863 pm and 63.2%, and 885 microm and 89.7%, for HM and DG, respectively. DMI was lower for HM compared to DG treatment in high-starch diets (20.8 vs 22.5 kg/d), but similar for the HM and DG treatments in low-starch diets (19.7 vs 19.6 kg/d). This reduction in DMI is attributed to smaller meal size for HM compared to DG in high-starch diets (1.9 vs 2.3 kg of DM for high-starch diets; 2.1 vs 2.0 kg of DM for low-starch diets). Faster starch fermentation for HM in high-starch diets might result in satiety with smaller meal size. Milk yield was greater when cows were fed high-starch diets compared to low-starch diets (38.6 vs 33.9 kg/d) regardless of corn grain treatment. High-starch diets increased solids-corrected milk yield by 3.3 kg (35.2 vs 31.9 kg/d) compared to low-starch diets for cows fed DG, but did not increase for cows fed HM. This was because of a lower milk fat concentration for cows fed HM in high-starch diets. Reducing ruminal starch fermentation by substituting DG for HM can increase the productivity of lactating cows fed high-starch diets.

Effects of corn grain conservation method on ruminal digestion kinetics for lactating dairy cows at two dietary starch concentrations

Effects of conservation method of corn grain and dietary starch concentration on ruminal digestion kinetics were evaluated. Eight ruminally and duodenally cannulated Holstein cows (55 +/- 15.9 days in milk; mean +/- SD) were used in a duplicated 4 x 4 Latin square design with a 2 x 2 factorial arrangement of treatments. Experimental diets contained either ground high moisture corn (HM) or dry ground corn (DG) at two dietary starch concentrations (32 vs. 21%). Mean particle size and dry-matter concentration of corn grain were 1,863 microm and 63.2%, and 885 microm and 89.7%, for HM and DG, respectively. Starch digestibility in the rumen was greater for HM treatments compared with DG treatments, but starch digestibility in the total tract was not affected by conservation method of corn grain because of compensatory digestion in the intestines. The difference in ruminal starch digestibility between HM and DG treatment was greater for high-starch diets (71.1 vs. 46.9%) compared with low-starch diets (58.5 vs. 45.9%). This interaction is attributed to a greater difference in first-order digestion rate of starch between HM and DG treatment in high-starch diets (28.2 vs. 14.6%/h) compared with low-starch diets (16.8 vs. 12.2%/h). This suggests that ruminal starch digestion is a second-order reaction limited by enzyme activities as well as substrate availability; ruminal contents of cows fed low-starch diets may have insufficient amylolytic activity for maximal starch digestion when readily fermentable starch is available. Rate of neutral detergent fiber digestion in the rumen was slower for high-starch diets and HM treatments compared with low-starch diets and DG treatments, respectively. Effects of corn grain conservation method on ruminal digestion kinetics are greatly altered by starch concentration of diets.

Effects of pretrial milk yield on responses of feed intake, digestion, and production to dietary forage concentration

The relationships between pretrial milk yield and effects of dietary forage-to-concentrate ratio on dry matter intake (DMI), digestion, and milk yield were evaluated using 32 Holstein cows in a crossover design with two 16-d periods. Cows were 197 +/- 55 (mean +/- SD) days in milk at the beginning of the experiment. Milk yield averaged 33.9 kg/d and ranged from 16.5 to 55.0 kg/d for the 4 d before initiation of treatments. Treatments were diets with forage-to-concentrate ratios of 67:33 and 44:56. Forages were alfalfa silage and corn silage, each at 50% of forage dry matter (DM). Neutral detergent fiber (NDF) concentrations of high-forage and low-forage diets were 30.7 and 24.3% of DM, respectively. Dry matter intake was 1.7 kg/d higher for cows fed the low-forage diet. Milk yield was 2.3 kg/d greater on low forage than on high forage, but 3.5% fat-corrected milk yield and yield of milk fat were not different between treatments. Individual DMI response to the low-forage diet relative to the high-forage diet (low-high) was positively and linearly related to pretrial fat-corrected milk yield, but fat-corrected milk yield response demonstrated a quadratic relationship with pretrial fat-corrected milk yield. Milk yield responded more positively to low forage among low- and high-producing cows than among moderate-producing cows. Energy partitioned to body reserves and to milk, and passage rate of indigestible NDF, also responded to dietary forage level in quadratic relationships with pretrial milk energy output. Individual responses of intake, production, and fiber digestion to a change in forage-to-concentrate ratio were dependent on production level.

Neutral detergent fiber concentration of corn silage and rumen inert bulk influences dry matter intake and ruminal digesta kinetics of growing steers

Corn silage with high NDF concentration has the potential to reduce DMI because it has a greater filling effect in the rumen than low-NDF corn silage. Our objective was to determine whether ruminal fill influences DMI to the same extent with low- or high-NDF corn silage-based diets. Eight ruminally cannulated Holstein steers (198 +/- 13 kg) were randomly assigned to a 2 x 2 factorial arrangement of treatments in a replicated 4 x 4 Latin square design with 16-d periods. Treatments were diets containing corn silage from a normal hybrid (low-fiber; LF) or its male-sterile isogenic counterpart (high-fiber; HF), offered for ad libitum consumption to steers with or without rumen inert bulk (RIB). The LF and HF diets contained 33.8 and 50.8% dietary NDF, respectively. Rumen inert bulk was added at 25% of pretrial ruminal volume in the form of plastic-coated tennis balls filled with sand to achieve a specific gravity of 1.1 and a total volume of 7.5 L. No fiber level x inert bulk interactions were detected for DMI or NDF intake (P > 0.10), suggesting that DMI was limited to the same extent by physical fill at both levels of dietary fiber. Addition of RIB decreased DMI by an average of 10.7%, which was 65.5 g/L of added bulk. The HF diet depressed DMI by an average of 15.5%, increased NDF intake 27.1%, and reduced ruminal NDF turnover time by 21.0% compared to the LF diet (P < 0.01), with no effect on ruminal volume or amount of NDF in the rumen (P > 0.10). Addition of RIB also reduced ruminal NDF turnover time and amount of NDF in the rumen (11.8% and 20.7%, respectively; P < 0.01), with no change in ruminal digesta volume (P > 0.10). The HF treatment decreased digestibility of DM and GE (5.5 and 5.7%, respectively; P < 0.01) but increased NDF digestibility (10.4%; P < 0.01) compared to LF. Rumen inert bulk had no effect on digestibility of DM, NDF, or GE (P > 0.10). The lack of reduction in digesta volume with addition of inert fill suggests that DMI of light-weight steers receiving corn silage-based diets within a wide range of NDF concentrations was not regulated by ruminal distension alone.

Neutral detergent fiber concentration in corn silage influences dry matter intake, diet digestibility, and performance of Angus and Holstein steers

Twelve Angus (237 +/- 13 kg) and twelve Holstein (235 +/- 15 kg) steers were used to determine whether corn silage-based diets with different NDF levels influence DMI to a similar extent in Angus and Holstein steers and as body weight of the steers increase. Steers were randomly assigned to individual slatted-floor pens and used in a crossover design consisting of six 14-d periods. Experimental diets contained corn silage from a normal hybrid (low-fiber; LF) and its male-sterile counterpart (high-fiber; HF) and were alternated each period. The LF and HF diets contained 33.8 and 50.8% NDF, respectively. The HF diet decreased (P < 0.01) overall steer mean DMI 14.0% relative to LF, with mean differences increasing as steers increased in BW (P < 0.01). Feeding the HF diet also reduced ADG by an average of 13.8% relative to the LF diet (P < 0.01). Holstein steers consumed 14.4% more DM and gained 14.3% faster (P < 0.01) than Angus steers. There was a fiber level x breed-type interaction (P = 0.08) for efficiency of gain. Angus steers receiving the HF diet had greater efficiency of gain than Angus steers consuming the LF diet; however, Holstein steers consuming the LF diet had greater efficiency of gain than those receiving the HF diet. The HF treatment reduced total-tract digestibility of DM and GE by 4.6 and 4.5%, respectively (P < 0.01), and decreased DE intake by 20.5% (P < 0.01) but increased apparent totaltract digestibility of NDF and ADF (9.4 and 8.4%, respectively; P < 0.01). Holstein steers had similar digestibility of DM and GE (P > 0.10) but had greater DE intake (P < 0.01) compared to Angus steers. There were fiber level x breed-type interactions for total-tract digestibility of NDF and ADF (P < 0.06). The difference in DM digestibility was negatively associated with the difference in DMI (r2 = 0.23; P < 0.01) for LF minus HF within Angus steers, but not within Holstein steers (P = 0.42). Total-tract digestibility of NDF and ADF was 4.1 and 3.4% lower for the HF diet but was only 1.1 and 0.6% lower for the LF diet when fed to Holstein compared to Angus steers. Results from this trial demonstrate that high-NDF corn silage-based diets reduced intake of both Angus and Holstein steers, and this reduction in DMI continued as steers increased in BW from 235 to 330 kg. Breed differences were also noted for digestible energy intake as influenced by fiber level.

Lobar torsion after pulmonary resection: presentation and outcome

OBJECTIVE

We reviewed our experience on postoperative lobar torsion.

METHODS

Between January 1972 and January 1998, 7887 patients underwent pulmonary resection at our institution. Seven (0.089%; 4 women and 3 men; median age, 68 years) patients required surgical reintervention for lobar torsion.

RESULTS

The indications for pulmonary resection were non-small cell carcinoma in 5 patients, lymphoma in 1 patient, and metastatic prostate carcinoma in 1 patient. The right upper lobe was resected in 3 patients, the left lower lobe in 2 patients, and the right middle and right lower lobe in 1 patient each. Postoperative radiographs demonstrated pulmonary infiltrates and volume loss in 5 patients and complete opacification in 2 patients. The median white blood cell count was 10.6 x 10(9) cells/L (range, 9.3-14.9 x 10(9) cells/L), and the median peak temperature was 38.4 degrees C (range, 37.8 degrees C-40.2 degrees C) during the first 48 hours postoperatively. The diagnosis of lobar torsion was made a median of 10 days (range, 2-14 days) after the initial operation; 4 patients underwent completion pneumonectomy, and 3 had lobectomy. Median hospitalization was 24 days and ranged from 10 to 56 days. There were no postoperative deaths. Complications after reoperation included respiratory failure in 2 patients, atrial arrhythmia in 2 patients, and empyema, urinary tract infection, and a transient ischemic attack in 1 patient each.

CONCLUSIONS

Lobar torsion represents a difficult diagnostic dilemma in the early postoperative period after pulmonary resection. A high index of suspicion is necessary to avoid a delay in treatment. Late diagnosis results in further pulmonary resection and prolonged hospitalization in the majority of cases.

Laparoscopic repair of large paraesophageal hiatal hernia

BACKGROUND

The objective of this study was to analyze our initial results after laparoscopic repair of large paraesophageal hiatal hernias.

METHODS

Between October 1997 and May 2000, 37 patients (23 women, 14 men) underwent laparoscopic repair of a large type II (pure paraesophageal) or type III (combined sliding and paraesophageal) hiatal hernia with more than 50% of the stomach herniated into the chest. Median age was 72 years (range 52 to 92 years). Data related to patient demographics, esophageal function, operative techniques, postoperative symptomatology, and complications were analyzed.

RESULTS

Laparoscopic hernia repair and Nissen fundoplication was possible in 35 of 37 patients (95.0%). Median hospitalization was 4 days (range 2 to 20 days). Intraoperative complications occurred in 6 patients (16.2%) and included pneumothorax in 3 patients, splenic injury in 2, and crural tear in 1. Early postoperative complications occurred in 5 patients (13.5%) and included esophageal leak in 2, severe bloating in 2, and a small bowel obstruction in 1. Two patients died within 30 days (5.4%), 1 from delayed splenic bleeding and 1 from adult respiratory distress syndrome secondary to a recurrent strangulated hiatal hernia. Follow-up was complete in 31 patients (94.0%) and ranged from 3 to 34 months (median 15 months). Twenty-seven patients (87.1%) were improved. Four patients (12.9%) required early postoperative dilatation. Recurrent paraesophageal hiatal hernia occurred in 4 patients (12.9%). Functional results were classified as excellent in 17 patients (54.9%), good in 9 (29.0%), fair in 1 (3.2%), and poor in 4 (12.9%).

CONCLUSIONS

Laparoscopic repair of large paraesophageal hiatal hernias is a challenging operation associated with significant morbidity and mortality. More experience, longer follow-up, and further refinement of the operative technique is indicated before it can be recommended as the standard approach.

Surgical treatment of primary lung cancer with synchronous brain metastases

OBJECTIVES

The role of surgical resection for brain metastases from non-small cell lung cancer is evolving. Although resection of primary lung cancer and metachronous brain metastases is superior to other treatment modalities in prolonging survival and disease-free interval, resection of the primary non-small cell lung cancer and synchronous brain metastases is controversial.

METHODS

From January 1975 to December 1997, 220 patients underwent surgical treatment for brain metastases from non-small cell lung cancer at our institution. Twenty-eight (12.7%) of these patients underwent surgical resection of synchronous brain metastases and the primary non-small cell lung cancer.

RESULTS

The group comprised 18 men and 10 women. Median age was 57 years (range 35-71 years). Twenty-two (78.6%) patients had neurologic symptoms. Craniotomy was performed first in all 28 patients. Median time between craniotomy and thoracotomy was 14 days (range 4-840 days). Pneumonectomy was performed in 4 patients, bilobectomy in 4, lobectomy in 18, and wedge excision in 2. Postoperative complications developed in 6 (21.4%) patients. Cell type was adenocarcinoma in 11 patients, squamous cell carcinoma in 9, and large cell carcinoma in 8. After pulmonary resection, 17 patients had no evidence of lymph node metastases (N0), 5 had hilar metastases (N1), and 6 had mediastinal metastases (N2). Twenty-four (85.7%) patients received postoperative adjuvant therapy. Follow-up was complete in all patients for a median of 24 months (range 2-104 months). Median survival was 24 months (range 2-104). Survival at 1, 2, and 5 years was 64.3%, 54.0%, and 21.4%, respectively. The presence of thoracic lymph node metastases (N1 or N2) significantly affected 5-year survival (P =.001).

CONCLUSION

Although the overall survival for patients who have brain metastases from non-small cell lung cancer is poor, surgical resection may prove beneficial in a select group of patients with synchronous brain metastases and lung cancer without lymph node metastases.

Empyema and bronchopleural fistula after pneumonectomy: factors affecting incidence

BACKGROUND

Factors affecting the incidence of empyema and bronchopleural fistula (BPF) after pneumonectomy were analyzed.

METHODS

All patients who underwent pneumonectomy at the Mayo Clinic in Rochester, Minnesota, from January 1985 to September 1998 were reviewed. There were 713 patients (514 males and 199 females). Ages ranged from 12 to 86 years (median 64 years). Indication for resection was primary malignancy in 607 patients (85.1%), metastatic disease in 32 (4.5%), and benign disease in 74 (10.4%). One hundred fifteen patients (16.1%) underwent completion pneumonectomy. Factors affecting the incidence of postoperative empyema and BPF were analyzed using univariate and multivariate analysis.

RESULTS

Empyema was documented in 53 patients (7.5%; 95% confidence interval [CI], 5.7% to 9.7%) and a BPF in 32 (4.5%; 95% CI, 3.1% to 6.3%). Univariate analysis demonstrated that the development of empyema was adversely affected by benign disease (p = 0.0001), lower preoperative forced expiratory volume in 1 second (FEV1; p < 0.01) and diffusion capacity of lung to carbon monoxide (DLCO; p = 0.0001), lower preoperative serum hemoglobin (p = 0.05), right pneumonectomy (p = 0.0109), bronchial stump reinforcement (p = 0.007), completion pneumonectomy (p < 0.01), timing of chest tube removal (p = 0.01), and the amount of blood transfusions (p < 0.01). Similarly, the development of BPF was significantly associated with benign disease (p = 0.03), lower preoperative FEV1 (p = 0.03) and DLCO (p = 0.01), right pneumonectomy (p < 0.0001), bronchial stump reinforcement (p = 0.03), timing of chest tube removal (p = 0.004), increased intravenous fluid in the first 12 hours (p = 0.04), and blood transfusions (p = 0.04). Bronchial stump closure with staples had a protective effect against BPF compared with suture closure (p = 0.009). No risk factors were identified as being jointly significant in multivariate analysis.

CONCLUSIONS

Multiple perioperative factors were associated with an increased incidence of empyema and BPF after pneumonectomy. Prophylactic reinforcement of the bronchial stump with viable tissue may be indicated in those patients suspected at higher risk for either empyema or BPF.

Pneumonectomy for malignant disease: factors affecting early morbidity and mortality

OBJECTIVE

The purpose of this report is to analyze factors affecting morbidity and mortality after pneumonectomy for malignant disease.

METHODS

We retrospectively reviewed the cases of all patients who underwent pneumonectomy for malignancy at the Mayo Clinic. Between January 1, 1985, and September 30, 1998, 639 patients (469 men and 170 women) were identified. Median age was 64 years (range 20 to 86 years). Indication for pneumonectomy was primary lung cancer in 607 (95.0%) patients and metastatic disease in 32 (5.0%). Factors affecting morbidity and mortality were analyzed by univariate and multivariate analysis.

RESULTS

Cardiopulmonary complications occurred in 245 patients (38.3%; 95% confidence interval 34.6%-42.2%). Factors adversely affecting morbidity with univariate analysis included age (P <.0001), male sex (P =.04), associated respiratory (P =.02) or cardiovascular disease (P <.0001), cigarette smoking (P =.02), decreased vital capacity (P =.01), forced expiratory volume in 1 second (P <.0001), forced vital capacity (P =.002), diffusion capacity of the lung to carbon monoxide (P =.005), oxygen saturation (P <.05), arterial PO (2) (P =.007), preoperative radiation (P =.02), bronchial stump reinforcement (P =.007), crystalloid infusion (P =.01), and blood transfusion (P =.02). Factors adversely affecting morbidity with multivariate analysis included age (P =.0001), associated cardiovascular disease (P =.001), and bronchial stump reinforcement (P =.0005). There were 45 deaths (7.0%; 95% confidence intervals 5.2%-9.3%). Factors adversely affecting mortality with univariate analysis included associated cardiovascular (P <.0001) or hematologic disease (P <.005), lower preoperative serum hemoglobin level (P =.004), preoperative chemotherapy (P =.01), decreased diffusion capacity of lung to carbon monoxide (P =.002), right pneumonectomy (P =.0006), extended resection (P =.04), bronchial stump reinforcement (P =.007), and crystalloid infusion (P =.01). Factors affecting mortality with multivariate analysis included hematologic disease (P =.01), lower preoperative serum hemoglobin (P =.003), and completion pneumonectomy (P =.01).

CONCLUSION

Multiple factors adversely affected morbidity and mortality after pneumonectomy for malignant disease. Appropriate selection and meticulous perioperative care are paramount to minimize risks in those patients who require pneumonectomy.

Ivor Lewis esophagogastrectomy for esophageal cancer

BACKGROUND

To examine the efficacy of the Ivor Lewis esophagogastrectomy for esophageal carcinoma prior to the widespread use of preoperative chemotherapy and irradiation, we reviewed our experience.

METHODS

We reexamined the cases of 220 consecutive patients who underwent an Ivor Lewis esophagogastrectomy for esophageal cancer from January 1992 through December 1995.

RESULTS

There were 196 men (89.1%) and 24 women. Median age was 65 years (range, 29 to 85 years). The results of pathological study showed adenocarcinoma in 188 patients (85.5%), squamous cell carcinoma in 31 (14.1%), and leiomyosarcoma in 1 patient (0.5%). Postsurgical staging was as follows: stage 0 in 10 patients, stage I in 19, stage IIa in 38, stage IIb in 28, stage III in 111, and stage IV in 14. The operative mortality rate was 1.4% (3 patients), and complications occurred in 83 patients (37.7%). Follow-up was 98.6% complete. Median survival for operative survivors was 1.9 years (range, 32 days to 8.7 years). The overall 5-year survival rate was 25.2%; it was 80% for patients in stage 0, 94.4% for those in stage I, 36.0% for those in stage IIa, 14.3% for patients in stage IIb, 10% for those in stage III and 0% for patients in stage IV.

CONCLUSIONS

Ivor Lewis esophagogastrectomy for esophageal cancer is a safe operation. Long-term survival is stage dependent. The low survival associated with advanced cancers should stimulate the search for effective neoadjuvant therapy.

Surgical treatment of hepatic and pulmonary metastases from colon cancer

BACKGROUND

Surgical resection of isolated hepatic or pulmonary metastases secondary to colorectal cancer has been shown to yield acceptable long-term survival. However, results are inconclusive for surgical resection of both hepatic and pulmonary metastases.

METHODS

We reviewed the records of all patients who underwent surgical resection of both hepatic and pulmonary metastases from colorectal cancer between 1980 and 1998.

RESULTS

A total of 58 patients underwent resection of both hepatic and pulmonary metastases secondary to colorectal cancer. All patients had local control of their primary cancer before metastasectomy. There were no operative deaths. Morbidity occurred in 12% of patients. Follow-up was complete in all patients, with a median duration of 62 months (range, 6 to 201 months). The 5- and 10-year survivals were 30% and 16%, respectively. A premetastasectomy carcinoembryonic antigen level greater than 5 ng/mL increased the risk of early death (p = 0.029). Neither the number of pulmonary lesions nor the time interval between the primary surgery and the metastasectomy had a significant impact on survival (p = 0.67). At 5 years, 55% of patients were free of disease. Four patients had lymph node involvement at the time of pulmonary resection and all 4 patients died within 22 months of their pulmonary metastasectomy.

CONCLUSIONS

Resection of both hepatic and pulmonary metastases secondary to colorectal cancer in highly selected patients is safe and results in long-term survival. Thoracic lymph node involvement and elevated carcinoembryonic antigen levels before pulmonary metastasectomy are associated with reduced survival.

Stage II (T3) lung cancer

The tumors classified under T3 are diverse and usually present a difficult problem; however, with the improvements in surgery, radiation, and systemic therapies described above, a significant improvement in survival and quality of life can be anticipated for the future.

High short-term mortality following lung biopsy for usual interstitial pneumonia

Usual interstitial pneumonia (UIP) is a specific histological pattern of interstitial pneumonia most often associated with the clinical syndrome of idiopathic pulmonary fibrosis (IPF). There is controversy regarding the use of surgical lung biopsy in the diagnosis of UIP, and the risk of lung biopsy in these patients is largely unknown. This study investigated the 30 day surgical mortality rate in patients undergoing surgical lung biopsy for UIP. Patients undergoing surgical lung biopsy over a 10-yr period from 1986-1995 with the ultimate diagnosis of UIP (with or without underlying connective tissue disease) were identified. Pathology, computed tomography, medical records, and survival were assessed. Ten of sixty patients with usual interstitial pneumonia were found to be dead within 30 days of surgical biopsy. All of these were patients with idiopathic UIP, unassociated with connective tissue disease (clinical condition of IPF). In conclusion, patients with usual interstitial pneumonia of the idiopathic type, who present with atypical features, may be at higher risk for death following surgical biopsy than patients presenting with more typical features or patients with other interstitial illnesses.

Management of postpneumonectomy empyema and bronchopleural fistula

Empyema after pneumonectomy is often associated with a bronchopleural fistula (BDF) and has a significant mortality. Management options include systemic antibiotics and observation, adequate pleural drainage, appropriate parenteral antibiotics, removal of necrotic tissue, and obliteration of residual pleural space. We prefer to treat the empyema with the procedure originally described by Clagett and Geraci in 1963. They demonstrated that postpneumonectomy empyema could be successfully treated by open pleural drainage, frequent wet-to-dry dressing changes, and when the thorax was clean, secondary chest wall closure with obliteration of the pleural cavity with an antibiotic solution. Failure was most often caused by a persistent or recurrent fistula. Because of this, when a BPF is present, the original Clagett technique was modified to include transposition of a well-vascularized muscle to cover the stump at the time of open drainage to prevent further ischemia and necrosis. Our preference is intrathoracic transposition of extrathoracic skeletal muscle. The goals of therapy for postpneumonectomy empyema remain a healthy patient with a a healed chest wall and no evidence of drainage or infection. Excellent results can be obtained in more than 80% of patients by using the Clagett procedure and intrathoracic muscle transposition when a BPF is present.

Adenosine kinase of Arabidopsis. Kinetic properties and gene expression

To assess the functional significance of adenosine salvage in plants, the cDNAs and genes encoding two isoforms of adenosine kinase (ADK) were isolated from Arabidopsis. The ADK1- and ADK2-coding sequences are very similar, sharing 92% and 89% amino acid and nucleotide identity, respectively. Each cDNA was overexpressed in Escherichia coli, and the catalytic activity of each isoform was determined. Both ADKs had similar catalytic properties with a K(m) and V(max)/K(m) for adenosine of 0.3 to 0.5 microM and 5.4 to 22 L min(-1) mg(-1) protein, respectively. The K(m) and V(max)/K(m) for the cytokinin riboside N(6)(isopentenyl) adenosine are 3 to 5 microM and 0.021 to 0.14 L min(-1) mg(-1) protein, respectively, suggesting that adenosine is the preferred substrate for both ADK isoforms. In Arabidopsis plants, both ADK genes are expressed constitutively, with the highest steady-state mRNA levels being found in stem and root. ADK1 transcript levels were generally higher than those of ADK2. ADK enzyme activity reflected relative ADK protein levels seen in immunoblots for leaves, flowers, and stems but only poorly so for roots, siliques, and dry seeds. The catalytic properties, tissue accumulation, and expression levels of these ADKs suggest that they play a key metabolic role in the salvage synthesis of adenylates and methyl recycling in Arabidopsis. They may also contribute to cytokinin interconversion.

Esophageal reconstruction for benign disease: self-assessment of functional outcome and quality of life

BACKGROUND

Little information exists regarding functional outcome and quality of life after esophagectomy and subsequent esophageal reconstruction for benign disease as evaluated by the patients themselves.

METHODS

Eighty-one patients completed a combined two-part questionnaire regarding esophageal function and quality of life (MOS SF-36) a median of 9.8 years (range, 10 months to 18.9 years) after esophageal reconstruction for benign disease. There were 43 men (53.1%) and 38 women (46.9%). Median age at time of esophageal reconstruction was 51 years (range, 6 to 78 years). Intestinal continuity was established with stomach in 58 patients (71.6%), colon in 16 patients (19.8%), and small bowel in 7 patients (8.6%).

RESULTS

Dysphagia to solids was present in 48 patients (59.3%) and 27 patients (33.3%) required at least one postoperative dilatation. Heartburn was present in 50 patients (61.7%) which required medication for control in 37 patients (45.7%). The number of meals per day was three to four in 58 patients (71.6%), more than four in 15 patients (18.5%), less than three in 6 patients (7.4%), and unknown in 2 patients (2.5%). The size of each meal was smaller than preoperatively in 46 patients (56.8%), larger in 22 patients (27.2%), unchanged in 12 patients (14.8%), and unknown in 1 patient (1.2%). The number of bowel movements per day increased in 37 patients (45.7%), was unchanged in 36 patients (44.4%), and decreased in 8 patients (9.9%). Resection for perforation was associated with smaller postoperative meals compared with resection for stricture (p < 0.05). Age, sex, and type of esophageal reconstruction did not affect late functional outcome. Regarding quality of life, physical functioning, social functioning, and health perception were decreased (p < 0.05). No significant change was observed in role-physical, mental health, bodily pain, energy/fatigue, and role-emotional scores.

CONCLUSIONS

Self-assessment of postoperative esophageal symptoms after esophagectomy and reconstruction for benign disease demonstrates that symptoms are frequently present at long-term follow-up and unaffected by the type of reconstruction.

Brown midrib-3 corn silage improves digestion but not performance of growing beef steers

The brown midrib-3 (bm3) gene mutation has been incorporated into corn plants to potentially improve fiber digestibility. The objectives of this study were to determine the effect of bm3 corn silage on digestion and performance of growing beef steers and to determine whether limiting intake would further enhance fiber digestibility of bm3 corn silage. A bm3 hybrid and its isogeneic normal counterpart were harvested at three-quarters kernel milk line. Neutral detergent fiber, ADF, and ADL were 4.5, 6.9, and 1.9 units lower, respectively, and DM was 5.4 units higher for bm3 than for normal silage. In Trial 1, eight ruminally fistulated Angus crossbred steers (224 +/- 24 kg) were randomly assigned to a 2 x 2 factorial arrangement of treatments in a replicated 4 x 4 Latin square design. Steers had ad libitum feed access or were restricted to 80% of ad libitum intake of diets containing 86% normal corn silage (Control) or bm3 corn silage (BMCS). The remainder of the diets consisted of soybean meal, urea, monensin, vitamins, and minerals. Dry matter intake was greater (P < 0.01) for steers offered ad libitum access to BMCS than for those with ad libitum access to the Control diet. The BMCS treatment resulted in improved (P < 0.05) apparent total-tract digestibility of DM, OM, NDF, and ADF. Mean concentration of total VFA and molar proportions of acetate were increased (P < 0.05) by feeding BMCS. There tended to be a DMI x hybrid interaction (P = 0.16) for apparent total-tract digestibility of NDF. When diets were offered ad libitum, BMCS increased NDF digestibility by 10.5 percentage units compared with Control, but, when DMI was limited, BMCS increased NDF digestibility by 15.8 percentage units. In Trial 2, 128 steer contemporaries of those used in Trial 1 (245 +/- 13 kg) were offered ad libitum access to BMCS or Control diets as used in Trial 1. After a 112-d treatment period, concentrate in the diet was increased, and all steers were fed a common finishing diet. During the 112-d treatment period, steers receiving BMCS consumed 0.45 kg more DM/d (P < 0.05) and had similar ADG (P > 0.10), compared with those steers receiving the Control silage. This resulted in poorer (P < 0.01) feed efficiency for steers receiving BMCS. Finishing phase and overall performance of the steers was not different (P > 0.10) due to treatment. Although feeding BMCS in growth-phase diets resulted in increased daily DMI and improved digestibility of DM and fiber, it did not result in improved steer feedlot ADG compared with Control silage.

Esophageal reconstruction for benign disease: early morbidity, mortality, and functional results

BACKGROUND

Esophagectomy for benign disease is performed infrequently. We reviewed the Mayo Clinic's experience with patients who required esophageal reconstruction for benign esophageal disease.

METHODS

From March 1956 to October 1997, all patients who required resection and reconstruction for a benign condition of the esophagus were reviewed.

RESULTS

There were 255 patients (141 male, 114 female). Median age was 55 years (range, 2 to 100). The original diagnosis was an esophageal stricture in 108 patients (42%), primary motility disorder in 84 (33%), perforation in 36 (14%), hiatal hernia in 18 (7%), and other in 9 (4.0%). Reconstruction was with stomach in 168 patients (66%), colon in 70 (27%), and small bowel in 17 (7%). The anastomosis was intrathoracic in 144 patients (57%) and cervical in 111 (43%). There were 13 postoperative deaths (mortality 5%); 142 patients (56%) had at least one complication. Median hospitalization was 14 days (range, 6-95 days). Follow-up was complete in 226 patients (88.6%) for a median of 52 months (range, 1 month to 29 years). A total of 175 patients (77.4%) were improved. Functional results were classified as excellent in 72 patients (31.8%), good in 23 (10.2%), fair in 80 (35.4%), and poor in 51 (22.6%).

CONCLUSIONS

Esophageal reconstruction for benign disease resulted in functional improvement in a majority of patients. It can be done with low mortality and acceptable morbidity. Early morbidity is adversely affected by the diagnosis of perforation and the route through which the conduit is placed. Late functional outcome is adversely affected by the diagnosis of paraesophageal hernia and a cervical anastomosis.

Bronchobiliary fistula: principles of management

Bronchobiliary fistula is an uncommon entity. Recently, we encountered 2 patients with this problem. Both were treated successfully with resection of the involved pulmonary tissue and interposition of viable tissue between the lung and the fistulous tract. This approach, although invasive, provided a rapid resolution of the patients' problem.

Cholecystokinin mediates depression of feed intake in dairy cattle fed high fat diets

Two experiments were conducted to investigate the effects of 1) different concentrations of dietary fat and 2) i.v. administration of a cholecystokinin receptor antagonist (MK-329) on feed intake and plasma concentrations of hormones and metabolites in dairy cattle. In Experiment 1, 4 lactating Holstein cows were used in a 4 x 4 Latin square design. Treatments were diets with 1) no fat added, 2) 30 g fat/kg feed (calcium salts of long-chain fatty acids as fat supplement), 3) 60 g fat/kg, and 4) 90 g fat/kg added. Cows were fed once daily a diet of concentrate, corn silage, alfalfa haylage, and alfalfa pellets. Dry matter intake decreased linearly with increasing concentrations of dietary fat (P < 0.0001). Overall plasma concentrations of nonesterified fatty acids (P < 0.0001), triacylglycerol (P < 0.0006), and cholecystokinin (P < 0.02), increased linearly with each level of dietary fat, but there was a linear decrease in plasma insulin (P < 0.0008). In Experiment 2, 4 nonpregnant and nonlactating Holstein heifers were used in a cross-over design in a 2 x 2 factorial arrangement of treatments. Treatments were diet (fatty acids, 27 g/kg vs 103 g/kg diet dry matter) and i.v. injections (MK-329 vs vehicle). Heifers were fed once daily a total mixed ration of corn silage, cracked corn and soybean meal with or without fat supplement. Diets were switched by period and either MK-329 (70 microg/kg body weight) or its vehicle was injected i.v. at 2 hr postfeeding. Daily dry matter intake was decreased by feeding the high fat diet (P < 0.02) but was not affected by injections. Injection of MK-329, however, increased dry matter intake by 92% in heifers fed the high fat diet during the first 2 hr postinjection compared to vehicle injection. Plasma pancreatic polypeptide concentration was increased by the high fat diet at 2 hr postfeeding (P < 0.02) but was lowered by MK-329 at 1 hr postinjection (P < 0.001). Plasma insulin was lowered by the high fat diet (P < 0.01) but was not affected by injections. The elevated plasma cholecystokinin concentration may have mediated depressed feed intake of dairy cattle fed the high fat diets.

Effects of diet on short-term regulation of feed intake by lactating dairy cattle

Physical and chemical characteristics of dietary ingredients and their interactions can have a large effect on dry matter intake (DMI) of lactating cows. Physical limitations caused by distension of the reticulo-rumen or other compartments of the gastrointestinal tract often limit DMI of high producing cows or cows fed high forage diets. Fermentation acids also limit DMI from a combination of increased osmolality in the reticulo-rumen and specific effects of propionate, although the mechanisms are not clear. The specific physical and chemical characteristics of diets that can affect DMI include fiber content, ease of hydrolysis of starch and fiber, particle size, particle fragility, silage fermentation products, concentration and characteristics of fat, and the amount and ruminal degradation of protein. Site of starch digestion affects the form of metabolic fuel absorbed, which can affect DMI because absorbed propionate appears to be more hypophagic than lactate or absorbed glucose. Dry matter intake is likely determined by integration of signals in brain satiety centers. Difficulty in measurement and extensive interactions among the variables make it challenging to account for dietary effects when predicting DMI. However, a greater understanding of the mechanisms along with evaluation of animal responses to diet changes allows diet adjustments to be made to optimize DMI as well as to optimize allocation of diet ingredients to animals. This paper discusses some of the characteristics of dietary ingredients that should be considered when formulating diets for lactating dairy cows and when allocating feeds to different groups of animals on the farm.

Role of surgical resection in broncholithiasis

BACKGROUND

Broncholithiasis is an uncommon problem with life-threatening complications. The purpose of this study was to update our experience in patients with broncholithiasis managed by surgical intervention.

METHODS

From January 1984 to January 1998, 118 patients were diagnosed with broncholithiasis at our institution. We reviewed the medical records of those patients who underwent surgical treatment.

RESULTS

There were 47 patients (19 men and 28 women). Median age was 58 years (range, 18 to 90 years). Indications for operation were symptoms in 44 patients and abnormal roentgenograms in 3 patients. Operative procedures included lung resection in 30 patients, broncholithectomy with or without bronchoplasty in 16, and segmental bronchial resection in 1 patient. There were no operative deaths. Postoperative complications occurred in 16 patients (34%). Follow-up was complete in 46 patients (98%) and ranged from 11 to 165 months (median, 74 months). The 15-year actuarial survival did not differ significantly from that of a matched control group (p = 0.774). At follow-up, 28 patients (68.3%) were asymptomatic. Symptoms continued in 12 patients. Recurrent or persistent disease was documented in 6 patients (14.6%). The site of recurrence was in a new location in 3 patients, a previous site in 2, and unknown in 1 patient. Subsequent management included observation in 3 patients, bronchoscopic removal in 2, and bilobectomy in 1 patient.

CONCLUSIONS

Surgical resection for broncholithiasis is an effective method of management for this disease and can be done with low mortality and morbidity. Progression of the disease may lead to recurrence and further surgical intervention.

Effects of brown midrib 3 mutation in corn silage on productivity of dairy cows fed two concentrations of dietary neutral detergent fiber: 3. Digestibility and microbial efficiency

The effects of digestibility of corn silage neutral detergent fiber (NDF) and dietary NDF content on ruminal digestion kinetics, site of nutrient digestion, and microbial N production efficiency were evaluated with eight multiparous high producing dairy cows in a duplicated 4 x 4 Latin square design with 21-d periods. Experimental diets contained corn silage from a brown midrib (bm3) hybrid or its isogenic normal control at two concentrations of dietary NDF (29 and 38%). The NDF digestibility estimated by a 30-h in vitro fermentation was higher for bm3 corn silage by 9.4 units (55.9 vs. 46.5%). Neither ruminal nor total tract NDF digestibility was affected by corn silage treatment. The bm3 corn silage diet decreased starch digestibility in the rumen and in the total tract, but increased postruminal starch digestibility compared with control diet. The bm3 corn silage diets increased microbial N flow to the duodenum and tended to decrease ruminal ammonia concentration. Microbial efficiency was greater for cows fed bm3 corn silage in spite of lower ruminal pH. Higher efficiency of microbial nitrogen production might be attributed to faster passage rate of NDF for cows fed bm3 corn silage compared with those fed control corn silage. Higher in vitro NDF digestibility might predict enhanced NDF fragility and ease of NDF hydrolysis in vivo. Enhanced in vitro NDF digestibility does not necessarily result in increased NDF digestibility either in the rumen or in the total tract, but possibly increases rate of passage and DMI, improving efficiency of microbial N production.

Effects of brown midrib 3 mutation in corn silage on productivity of dairy cows fed two concentrations of dietary neutral detergent fiber: 1. Feeding behavior and nutrient utilization

The effects of digestibility of corn silage neutral detergent fiber (NDF) and dietary NDF content on feeding behavior, dry matter intake (DMI), and energy utilization were evaluated with eight multiparous high producing dairy cows in a duplicated 4 x 4 Latin square design with 21-d periods. Experimental diets contained corn silage from a brown midrib (bm3) hybrid or its isogenic normal control at two concentrations of dietary NDF (29 and 38%). Both low NDF diets and bm3 corn silage treatments increased DMI and milk yield. However, an interaction between corn silage treatment and dietary NDF content was observed for meal size and for interval between meals, implying that different mechanisms regulating DMI dominate depending on the fermentation characteristics of diets. The bm3 treatment depressed milk fat concentration when fed in a low NDF diet. The bm3 corn silage increased solids-corrected milk yield, but did not affect daily body weight gain compared with control, whereas low NDF diets increased daily body weight gain, but did not affect solids-corrected milk yield compared to high NDF diets. Both bm3 treatments and low NDF diets reduced ruminal pH, but low NDF treatments increased fluctuation of ruminal pH and bm3 treatments did not. Feeding bm3 corn silage increased the energy utilized for milk production, possibly because of a consistent supply of metabolic fuels from the rumen. The beneficial effects of bm3 corn silage on productivity of lactating cows were greater for the cows fed a high NDF diet.

Effects of brown midrib 3 mutation in corn silage on productivity of dairy cows fed two concentrations of dietary neutral detergent fiber: 2. Chewing activities

The effects of digestibility of corn silage neutral detergent fiber (NDF) and dietary NDF content on chewing activities were evaluated with eight multiparous high producing dairy cows in a duplicated 4 x 4 Latin square design with 21-d periods. Experimental diets contained corn silage from a brown midrib (bm3) hybrid or its isogenic normal control at two concentrations of dietary NDF (29 and 38%). The NDF digestibility estimated by 30-h in vitro fermentation was higher for bm3 corn silage by 9.4 units (55.9 vs. 46.5%). Feeding behavior of animals and ruminal pH were monitored continuously for 4 d in each period by a computerized data acquisition system. Ruminal digesta were evacuated twice per period to determine the ruminal NDF pool and its turnover rate. There was no effect of NDF digestibility on total chewing time either per day or per kilogram of NDF intake, or on ruminating time either per day or per kilogram of NDF intake. Although bm3 treatments increased the turnover rate of NDF in the rumen, they increased dry matter intake and had no effect on ruminal NDF pool size. Total chewing time and ruminating time per day were related positively to NDF intake and ruminal NDF pool size, but were not related to ruminal turnover rate of NDF. These results provide no evidence that enhanced NDF digestibility decreases the physical effectiveness of NDF of corn silage.

Primary non-Hodgkin's lymphoma of the lung

BACKGROUND

Primary non-Hodgkin's lymphoma of the lung is a rare entity. Although the prognosis is favorable, clinical features, prognostic factors, and patient management have not been clearly defined.

METHODS

We reviewed retrospectively the records of 48 patients operated on for primary pulmonary non-Hodgkin's lymphoma. The study group consisted of 21 male (44%) and 27 female (56%) patients with a mean age of 61.8 years. Thirty-seven and a half percent of patients were asymptomatic, and 62.5% were seen with pulmonary symptoms, systemic symptoms, or both. A definitive diagnosis was obtained by thoracotomy in 90% of patients, thoracoscopy in 8%, and anterior mediastinotomy in 2%.

RESULTS

Complete surgical resection was possible in 19 patients (40%). A mucosa-associated lymphoid tissue lymphoma (MALT) was found in 35 patients and lymphoma that was not of this type, in 13. The 1-year, 5-year, and 10-year survival rates were 91%, 68%, and 53%, respectively in the group with mucosa-associated lymphoid tissue lymphoma and 85%, 65%, and 64% in the group with lymphoma that was not of the mucosa-associated lymphoid tissue type. None of the prognostic factors studied (mode of presentation, smoking history, bilateral disease, postoperative stage, complete resection, adjuvant chemotherapy, histology) significantly influenced patient survival.

CONCLUSIONS

Primary non-Hodgkin's lymphoma of the lung occurs with nonspecific clinical features. Although patient survival is good, prognostic factors could not be identified.

A dairy herd model for use in whole farm simulations

A dairy herd submodel was created for integration with other farm submodels to form DAFOSYM, a dairy farm simulation model. The herd submodel determines the best mix of available feeds to meet the fiber, energy, and protein requirements for each of six animal groups. The groups are early-, mid-, late-, and nonlactating cows, heifers over 1 yr old, and younger heifers. Feed intake, milk production, and manure dry matter and nutrient (N, P, and K) excretions are functions of the nutrient content of the diets. Required feed characteristics include crude protein, rumen degradable protein, acid detergent insoluble protein, net energy of lactation, neutral detergent fiber, total digestible nutrients, P, and K concentrations. Feed intake is predicted with fill and roughage units. These units are functions of feed neutral detergent fiber adjusted for particle size distribution and the relative rate of ruminal digestibility or physical effectiveness of the fiber. The herd submodel predicted feed intakes, nutrient requirements, diets, and manure excretions similar to those recommended or measured for dairy animals. When integrated with other farm components in DAFOSYM, the comprehensive model provides a useful tool for evaluating the long-term performance and economics of alternative dairy farm systems.

Treatment of epiphrenic diverticula

Epiphrenic diverticulum is a rare disorder of the lower esophagus, thought to be related to an esophageal motility disorder. Treatment should involve removal of diverticulum and myotomy. Although the surgery is technically a difficult one, the long-term outcome should be excellent.

Effect of energy and protein density of prepartum diets on fat and protein metabolism of dairy cattle in the periparturient period

To determine if increased nutrient density in prepartum diets improves nutrient balance of peripartum cows, we blocked 40 Holstein cows and 40 heifers by expected date of parturition and assigned them randomly within blocks to one of four treatment diets varying in density of net energy for lactation (NEL) and crude protein (CP). Diets were 1.30 Mcal of NEL/kg and 12.2% CP, 1.49 Mcal of NEL/kg and 14.2% CP, 1.61 Mcal of NEL/kg and 15.9% CP, and 1.48 Mcal of NEL/kg and 16.2% CP. These diets were fed ad libitum from 25 d prepartum until parturition, and all cows were fed the same diet after calving. Increased nutrient-density of prepartum diets did not decrease feed intake. Compared to animals fed the lowest density, those fed the highest density consumed more NEL (20 vs. 14 Mcal/d) and gained more body condition, backfat, and body weight. They also had less nonesterified fatty acids in plasma (176 vs. 233 microM) and more insulin-like growth factor-I in plasma (472 vs. 390 ng/ml) during the last 2 wk prepartum and less triglyceride in liver at parturition (0.9 vs. 1.5%, wet tissue basis). Quadratic effects of energy density were not observed, and the addition of protein in the medium energy diet had no effect. Prepartum diets did not alter any variables during lactation. In conclusion, increasing the energy and protein density up to 1.6 Mcal of NEL/kg and 16% CP in diets during the last month before parturition improves nutrient balance of cattle prepartum and decreases hepatic lipid content at parturition.

Alpha1-antitrypsin deficiency allele carriers among lung cancer patients

Lung cancer (LC) and chronic obstructive pulmonary lung diseases (COPDs; including emphysema and chronic bronchitis) share a common etiology. Despite the known associations of alpha1-antitrypsin deficiency (alpha1AD) with COPD and COPD with LC, few studies examined the association of alpha1AD alleles and LC. We hypothesize that heterozygous individuals who carry a deficient allele of the alpha1AD gene Pi (protease inhibitor locus) are at an increased risk of developing LC. The Pi locus is highly polymorphic with >70 variants reported. There are at least 10 alleles associated with deficiency in alpha1-antitrypsin. Using an exact binomial test, we compared the alpha1AD carrier rate in 260 newly diagnosed Mayo Clinic LC patients to the reported carrier rate in Caucasians in the United States (7%). alpha1AD carrier status, determined by isoelectric focusing assay, was examined with respect to the history of cigarette smoking, COPD, and histological types. Thirty-two of the 260 patients (12.3%; 95% confidence interval, 8.6-16.9%) carried an alpha1AD allele, which was significantly higher than expected (P = 0.002). Twenty-four of the 32 carriers had allele S, 6 had allele Z, and 2 had allele I. Patients who never smoked cigarettes were three times more likely to carry a deficient allele (20.6%; P = 0.008), although smokers had a higher carrier rate (11.1%; P = 0.025) when compared with the 7% rate. Patients with squamous cell or bronchoalveolar carcinoma had a significantly higher carrier rate than expected (15.9% and 23.8%, P < or = 0.01, respectively). Our preliminary findings suggest that individuals who carry an alpha1AD allele may have an increased risk for developing LC, specifically squamous cell or bronchoalveolar carcinoma.

Inflammatory pseudotumors of the lung

BACKGROUND

Inflammatory pseudotumors of the lung are rare and often present a dilemma for the surgeon at time of operation. We reviewed our experience with patients who have this unusual pathology.

METHODS

Between February 1946 and September 1993, 56,400 general thoracic surgical procedures were performed at the Mayo Clinic. Twenty-three patients (0.04%) had resection of an inflammatory pseudotumor of the lung. There were 12 women and 11 men. Median age was 47 years (range, 5 to 77 years). Six patients (26%) were less than 18 years old. All pathologic specimens were re-reviewed, and the diagnosis of inflammatory pseudotumor was confirmed. Eighteen patients (78%) were symptomatic which included cough in 12, weight loss in 4, fever in 4, and fatigue in 4. Four patients had prior incomplete resections performed elsewhere and underwent re-resection because of growth of residual pseudotumor. Wedge excision was performed in 7 patients, lobectomy in 6, pneumonectomy in 6, chest wall resection in 2, segmentectomy in 1, and bilobectomy in 1. Complete resection was accomplished in 18 patients (78%). Median tumor size was 4.0 cm (range, 1 to 15 cm). There were no operative deaths. Follow-up was complete in all patients and ranged from 3 to 27 years (median, 9 years).

RESULTS

Overall 5-year survival was 91%. Nineteen patients are currently alive. Cause of death in the remaining 4 patients was unrelated to pseudotumor. The pseudotumor recurred in 3 of the 5 patients who had incomplete resection; 2 have had subsequent complete excision with no evidence of recurrence 8 and 9 years later.

CONCLUSIONS

We conclude that inflammatory pseudotumors of the lung are rare. They often occur in children, can grow to a large size, and are often locally invasive, requiring significant pulmonary resection. Complete resection, when possible, is safe and leads to excellent survival. Pseudotumors, which recur, should be re-resected.

Evaluation of the importance of the digestibility of neutral detergent fiber from forage: effects on dry matter intake and milk yield of dairy cows

Effects of the digestibility of neutral detergent fiber (NDF) from forage on performance of dairy cows were evaluated statistically using treatment means for 13 sets of forage comparisons reported in the literature. All comparisons reported significant differences in NDF digestibilities of forages in situ or in vitro. Treatment means were blocked by study or by additional factorial treatment within a study to remove variation among experiments. The statistical model included random effect of block, fixed factorial effect of NDF digestibility (high or low), and dietary NDF concentration as a covariate. Enhanced NDF digestibility of forage significantly increased dry matter intake (DMI) and milk yield. A one-unit increase in NDF digestibility in vitro or in situ was associated with a 0.17-kg increase in DMI and a 0.25-kg increase in 4% fat-corrected milk. Differences in NDF digestibility between treatments were greater when measured in vitro or in situ than when measured in vivo. Digestibility of NDF in vitro or in situ might be a better indicator of DMI than NDF digestibility in vivo because forages with high in vitro or in situ NDF digestibilities might have shorter rumen retention times, allowing greater DMI at the expense of NDF digestibility in vivo. Digestibility of NDF is an important parameter of forage quality.

Early and long-term results of prosthetic chest wall reconstruction

OBJECTIVE

The purpose of this report is to evaluate our results in patients who underwent prosthetic bony reconstruction after chest wall resection.

METHODS

We retrospectively reviewed all patients who underwent chest wall resection and reconstruction with prosthetic material at the Mayo Clinic.

RESULTS

From January 1, 1977, to December 31, 1992, 197 patients (109 male patients and 88 female patients) underwent chest wall resection and reconstruction with prosthetic material. Median age was 59 years (range, 11-86 years). The indication for resection was recurrent chest wall malignancy in 65 patients (33.0%), primary chest wall malignancy in 62 patients (31.5%), contiguous lung or breast carcinoma in 58 patients (29.4%), and other reasons in 12 patients (6.1%). Three patients (1.5%) each had an open draining wound. This review covers 2 time periods. Sixty-four patients (32.5%) underwent reconstruction with polypropylene mesh during the period from 1977 to 1986. One hundred thirty-three patients (67.5%) underwent reconstruction with polytetrafluoroethylene from 1984 to 1992. Soft tissue coverage was achieved with transposed muscle in 116 patients (58.9%), local tissue in 81 patients (41.1%), and omentum in 3 patients (1.5%). There were 8 deaths (operative mortality rate, 4.1%). Ninety-one patients (46.2%) experienced complications. Seromas occurred in 14 patients (7.1%). Wound infections occurred in 9 patients (4.6%; 5 patients with polypropylene mesh and 4 patients with polytetrafluoroethylene). The prosthesis was removed in all 5 patients with polypropylene mesh and in none of the patients with polytetrafluoroethylene. Follow-up was complete in 179 operative survivors (94.7%) and ranged from 1 to 204 months (median, 26 months). A well-healed asymptomatic wound was present in 127 patients (70.9%).

CONCLUSIONS

Chest wall resection and reconstruction with prosthetic material will yield satisfactory results in most patients. Little difference exists between polypropylene mesh and polytetrafluoroethylene.