Effects of brown midrib 3 mutation in corn silage on dry matter intake and productivity of high yielding dairy cows

The effects of enhanced in vitro neutral detergent fiber (NDF) digestibility of corn silage on dry matter intake (DMI) and milk yield were evaluated using 32 Holstein cows in a crossover design with 28-d periods. At the beginning of the experiment, cows were 89 d in milk and yielded 45.6 kg/d of milk. Experimental diets contained either brown midrib (bm3) corn silage or isogenic normal corn silage (control) at 44.6% of DM. The NDF digestibility estimated by 30-h in vitro fermentation was higher for bm3 corn silage by 9.7 units. Contents of NDF and lignin were lower for bm3 corn silage by 1.8 and 0.8 units, respectively. Diets were formulated to contain 19% crude protein and 31% NDF and to have a forage to concentrate ratio of 56:44. Daily DMI, milk yield (3.5% fat-corrected milk), and solids-corrected milk were 2.1, 2.6, and 2.7 kg higher, respectively, for cows fed bm3 corn silage. The milk protein and lactose contents were greater for bm3 treatment, but milk fat content was not. Individual milk yield responses of the cows to bm3 treatment were positively related to pretrial milk yield, and DMI response tended to be positively related to pretrial milk yield. Enhanced in vitro NDF digestibility was associated with higher energy intake, which resulted in increased milk yield.

Results of reoperation on the upper esophageal sphincter

OBJECTIVE

Reoperation on the upper esophageal sphincter is infrequent. We reviewed our experience in patients who underwent reoperation on the upper esophageal sphincter.

METHODS

This is a retrospective report of accumulative series from 2 separate institutions.

RESULTS

From September 1, 1976, to February 28, 1997, 37 patients underwent reoperation on the upper esophageal sphincter for recurrent or persistent obstructive symptoms. There were 29 men and 8 women. The median age was 69 years (range, 38-87 years). The original indication for the operation was a pharyngoesophageal (Zenker's) diverticulum in 33 patients (89.2%), oculopharyngeal dystrophy in 3 patients (8.1%), and muscular dystrophy in 1 patient (2.7%). One prior upper esophageal sphincter operation had been performed in 26 patients (70.3%), two operations in 9 patients (24. 3%), and three operations in 2 patients (5.4%). All patients were symptomatic; 35 patients (94.6%) had dysphagia; 23 patients (62.2%) had regurgitation; and 12 patients (32.4%) had episodes of aspiration. Thirty of the patients (91.0%) with Zenker's diverticulum were found to have a recurrent or persistent diverticulum at reoperation. A diverticulectomy and cricopharyngeal myotomy were performed in 23 patients (62.2%); cricopharyngeal myotomy alone, in 7 patients (18.9%); diverticulopexy and cricopharyngeal myotomy, in 6 patients (16.2%); and diverticulectomy alone, in 1 patient (2.7%). There were no operative deaths. Complications developed in 10 patients (27.0%). Follow-up was complete in 34 patients (91.9%) and ranged from 2 to 149 months (median, 39 mo). Thirty-two patients (94.1%) were improved. Functional results were classified as excellent in 26 patients (76. 5%), good in 2 patients (5.9%), fair in 4 patients (11.7%), and poor in 2 patients (5.9%).

CONCLUSIONS

Reoperation for patients who have persistent or recurrent symptoms after an operation on the upper esophageal sphincter is associated with acceptable morbidity and mortality rates. Resolution of symptoms occurs in most patients.

Modeling ruminal digestibility of carbohydrates and microbial protein flow to the duodenum

Carbohydrates are the major source of energy for dairy cows and for microbial protein synthesis in the rumen. The prediction of ruminal carbohydrate digestibility and of the flow of microbial protein to the small intestine is difficult because of the variability among various feeds in the kinetics of digestion and passage of neutral detergent fiber and starch. Disappearance of fiber and starch in vitro or in situ and gas production in vitro have been extensively evaluated, improved, and reviewed. Similarly, markers and models to measure ruminal passage rate have been extensively researched and improved. Sources of variation and decreased accuracy for these techniques are discussed. Variation and potential errors also remain for the prediction of microbial protein flow to the duodenum using in vivo procedures. However, when in vivo results were accumulated into a database, microbial N flow to the duodenum over a wide range of conditions could be predicted accurately by intake of net energy for lactation or by dry matter intake and percentage of neutral detergent fiber in the diet. Although evaluation of feeding interactions and specific dietary limitations for microbial protein production in the rumen are possible with some models but not with this regression approach, mechanistic models need further validation and more accurate rate constants for improved accuracy over a wide range of conditions.

Uncut Collis-Nissen fundoplication: learning curve and long-term results

BACKGROUND

Between September 1985 and July 1990, the first 100 consecutive patients (50 female and 50 male) undergoing primary uncut Collis-Nissen fundoplication performed by one surgeon were reviewed.

METHODS

Median age was 62 years and ranged from 19 to 89 years. Indications for repair included gastroesophageal reflux in 56 patients, obstructive symptoms in 34, and a combination of both in 10. An upper gastrointestinal endoscopy was performed in 99 patients; all were abnormal. Esophagitis was documented in 53 patients, large diaphragmatic hernia in 36, stenosis in 18, "Cameron's erosions" in 17, Barrett's disease in 13, and other findings in 9 patients. An abnormal upper gastrointestinal series was demonstrated in 96 of 97 patients evaluated. Motility studies were performed in 95 patients, and 11 had abnormal peristalsis. All procedures were performed through a left thoracotomy.

RESULTS

Complications occurred in 23 patients and included respiratory failure in 6, atrial fibrillation in 3, atelectasis in 3, pneumonia in 2, myocardial infarction in 2, and chylothorax, severe dysphagia, early breakdown of repair, cardiac tamponade, hematuria, spinal headache, and intraoperative perforation by dilator in 1 each. There were 2 postoperative deaths, both cardiac in origin. Median hospitalization was 8 days (range, 6 to 76 days). The first 25 patients had 10 complications (40%) and 2 deaths (8%). The remaining 75 patients had 13 complications (17%) and no deaths (mortality, p = 0.06; morbidity, p = 0.03). Follow-up was complete in all patients for a median of 100 months (range, 3 to 138 months). Eighty-six of the 98 operative survivors are currently alive. At last follow-up, excellent functional results were observed in 58 patients (59%), good in 24 (25%), fair in 8 (8%), poor in 7 (7%), and unknown in 1 (1%).

CONCLUSION

We conclude that the uncut Collis-Nissen fundoplication provides good to excellent long-term results in 84% of patients. Operative mortality and morbidity is acceptable but is associated with a learning curve.

Leiomyosarcoma of the esophagus: results of surgical treatment

BACKGROUND

This study examined the results of surgical treatment of leiomyosarcoma of the esophagus.

METHODS

Between January 1920 and December 1996, 17 patients (9 men and 8 women) with leiomyosarcoma of the esophagus were treated surgically at the Mayo Clinic. Median age was 58 years and ranged from 26 to 76 years. Symptoms included dysphagia in 11 patients (64.7%) and odynophagia in 6 (35.3%). The tumor was located in the middle third of the esophagus in 10 patients (58.8%) and in the cervical esophagus in 7 (41.2%). Procedures performed included esophagogastrectomy in 9 patients (Ivor Lewis in 5, left thoracoabdominal in 3, and transhiatal in 1), enucleation in 3, transgastric excision in 1, and exploration without resection in 4.

RESULTS

The procedure was considered curative in 11 patients (64.7%). There was one operative death (mortality, 5.9%). Complications occurred in 3 patients (17.6%) and included anastomotic leak in 2 and bleeding requiring reoperation in 1. Growth pattern was infiltrating in 7, polypoid in 5, and intramural in 5. Histologically, the tumor was grade 1 in 6 patients, grade 2 in 2, grade 3 in 7, and grade 4 in 2. The tumor was postsurgically classified as stage I in 2 patients, stage IIA in 7, stage IIB in 1, stage IIIA in 5, stage IV in 1, and unknown in 1. Six patients (35.3%) received adjuvant treatment. Follow-up was complete in 16 patients (94.1%) and ranged from 1 to 182 months (median, 48 months). Five- and 10-year actuarial survivals were 47.0% and 31.0%, respectively. Seven patients (41.2%) are currently alive (median survival, 72 months); all underwent curative resection. Factors affecting survival included completeness of resection, growth pattern, postsurgical stage, tumor grade, and tumor location (p < 0.05).

CONCLUSIONS

We conclude that leiomyosarcoma of the esophagus is rare. Complete resection provides long-term survival.

Zenker's diverticulum in the elderly: is operation justified?

BACKGROUND

Surgical correction of symptomatic Zenker's diverticulum is effective; however, elderly symptomatic patients may be denied surgical intervention because of perceived increased risks.

METHODS

To address this concern, we reviewed 75 patients (46 men and 29 women) found to have this condition during the past two decades.

RESULTS

Median age was 79 years (range, 75 to 91 years). Preoperative symptoms included dysphagia in 69 patients (92%), regurgitation in 61 (81%), pneumonia in 9 (12%), halitosis in 3 (4%), and weight loss in 1 (1%). Gastroesophageal reflux symptoms were noted in 27 patients (36%). Diagnosis was made by barium swallow in 63 patients, esophagoscopy in 5, and a combination of both in 7. Surgical procedures included both diverticulectomy and myotomy in 57 patients (76%), myotomy alone in 9 (12%), diverticulopexy and myotomy in 5 (7%), and diverticulectomy alone in 4 (5%). There was no in-hospital mortality. Complications occurred in 8 patients (11%) and included esophagocutaneous fistula in 4, pneumonia and urinary tract infection in 1, and wound infection, myocardial infarction, and persistent diverticulum in 1 each. Follow-up was available in 72 patients (96%) and ranged from 8 days to 17 years (median, 3.3 years). At follow-up, 64 patients (88%) were asymptomatic and 4 (6%) were improved with minimal symptoms. The remaining 4 patients (6%) have had varying degrees of dysphagia and all have been treated with periodic esophageal dilations.

CONCLUSIONS

Operation for symptomatic Zenker's diverticulum in the elderly is safe and effective and will result in resolution of symptoms and improved quality of life in most patients.

Open repair of hiatus hernia: thoracic approach

Open repair of a hiatal hernia remains an excellent method for correction of symptomatic gastroesphageal reflux. This article gives a technical description of the performance of the Belsey Mark IV hiatal herniorrhaphy and the uncut Collis-Nissen repair. A brief description of preoperative evaluation and results is also included.

Early experience and learning curve associated with laparoscopic Nissen fundoplication

BACKGROUND

Laparoscopic approach for hiatal hernia repair is relatively new. Information on the learning curve is limited.

METHODS

From January 1994 to September 1996, 280 patients underwent antireflux surgery at our institution. A laparoscopic repair was attempted in 60 patients (21.4%). There were 38 men and 22 women. Median age was 49 years (range 21 to 78 years). Indications for operation were gastroesophageal reflux in 59 patients and a large paraesophageal hernia in one. A Nissen fundoplication was performed in all patients; 53 (88.3%) had concomitant hiatal hernia repair.

RESULTS

In eight patients (13.3%) the operation was converted to an open procedure. Median operative time for the 52 patients who had laparoscopic repair was 215 minutes (range 104 to 320 minutes). There were no deaths. Complications occurred in five patients (9.6%). Median hospitalization was 2 days (range 1 to 5 days). Median operative time and median hospitalization were significantly longer in the first 26 patients than in the subsequent 25 patients (248 vs 203 minutes and 2 days vs 1 day, respectively; p = 0.03). Seven of the first 30 patients (23.3%) required laparotomy as compared with two of the second 30 (6.7%) (p = 0.07). Follow-up in the 51 patients who had laparoscopic fundoplication for reflux was complete in 50 (98.0%) and ranged from 7 to 38 months (median 13 months). Functional results were classified as excellent in 34 patients (68.0%), good in 6 (12.0%), fair in 7 (14.0%), and poor in 3 (6.0%). Three patients were reoperated on for recurrent reflux symptoms at 5, 5, and 11 months.

CONCLUSIONS

We conclude that laparoscopic Nissen fundoplication can be performed safely. The operative time, hospitalization, and conversion rate to laparotomy are higher during the early part of the experience, but all are reduced after the learning curve.

Effectiveness of postoperative irradiation in stage IIIA non-small cell lung cancer according to regression tree analyses of recurrence risks

BACKGROUND

In the setting of grossly resected stage IIIA (N2 involvement) non-small cell lung carcinoma, the role of adjuvant postoperative thoracic radiation therapy (TRT) remains controversial. This study was initiated to subcategorize these patients into high-, intermediate-, and low-risk groups with respect to local recurrence and survival rates, and to determine whether there were certain subgroups of patients who were particularly likely or unlikely to benefit from postoperative TRT.

METHODS

Two hundred twenty-four patients were studied. A regression tree analysis was used to separate patients who had undergone operation alone into groups that had a high, intermediate, or low risk of local recurrence and death. The effect of adjuvant postoperative TRT then was examined in each of these groups.

RESULTS

The use of adjuvant postoperative TRT (compared with operation alone) was associated with an improvement in freedom from local recurrence and survival for patients who had an intermediate or high risk of local recurrence and death. However, the greatest level of improvement in freedom from local recurrence (p < 0.0001) and survival (p = 0.0002) associated with the use of adjuvant postoperative TRT was in the high-risk group. Similarly, but of lesser magnitude, the intermediate-risk group had improved freedom from local recurrence and survival rates with the use of adjuvant post-operative TRT (p = 0.002 and p = 0.01, respectively). For the low-risk group, the freedom from local recurrence and survival rates were not statistically different between the patients who received adjuvant postoperative TRT and those who underwent observation.

CONCLUSIONS

Patients with non-small cell lung carcinoma involving ipsilateral mediastinal lymph nodes (stage IIIA) who undergo gross resection and who are at either high or intermediate risk for local recurrence and death are likely to benefit from adjuvant postoperative irradiation. The role of radiation therapy in low-risk patients is unclear. Prospective confirmation of these observations is warranted.

The impact of surgical adjuvant thoracic radiation therapy for patients with nonsmall cell lung carcinoma with ipsilateral mediastinal lymph node involvement

BACKGROUND

Previous nonsmall cell lung carcinoma studies have shown that patients with ipsilateral mediastinal (N2) lymph node involvement who underwent surgical resection have a greater local recurrence rate than those with less lymph node involvement (N0, N1). Therefore, it was hypothesized that complete surgical clearance of subclinical lymph node disease is difficult in N2 patients and that adjuvant postoperative thoracic radiotherapy (TRT) may be beneficial.

METHODS

A retrospective review was performed to determine the local recurrence and survival rates for patients with N2 disease undergoing complete surgical resection with or without adjuvant TRT. Between 1987 and 1993 at the Mayo Clinic, 224 patients underwent complete resection of N2 nonsmall cell lung carcinoma. More than one mediastinal lymph node station was sampled in 98% of patients; 39% then received adjuvant TRT (median dose, 50.4 grays).

RESULTS

The median follow-up time was 3.5 years for the patients who were alive at the time of the analysis. The surgery alone versus surgery plus TRT groups were well balanced with respect to gender, age, histology, tumor grade, number of mediastinal lymph node stations dissected or involved, and involved N1 lymph node number. There were slightly more patients with right lower lobe lesions (compared with other lobes), patients with multiple lobe involvement, and patients with only one N2 lymph node involved in the surgery alone group. After treatment with surgery alone, the actuarial 4-year local recurrence rate was 60%, compared with 17% for treatment with adjuvant TRT (P < 0.0001). The actuarial 4-year survival rate was 22% for treatment with surgery alone, compared with 43% for treatment with adjuvant TRT (P = 0.005). On multivariate analysis, the addition of TRT (P = 0.0001), absence of superior mediastinal lymph node involvement (P = 0.005), and fewer N1 lymph nodes involved (P = 0.02) were independently associated with improved survival rate.

CONCLUSIONS

This study, which to the authors' knowledge is the largest evaluating adjuvant TRT in N2 nonsmall cell lung carcinoma, suggests that adjuvant TRT may improve local control and survival.

Physical effectiveness of the neutral detergent fiber of whole linted cottonseed relative to that of alfalfa silage at two lengths of cut

The effectiveness of the neutral detergent fiber (NDF) of whole linted cottonseed to stimulate chewing was examined relative to the effectiveness of the NDF of alfalfa silage at two lengths of cut. Twelve Holstein cows (125 d of lactation) were fed diets containing alfalfa silages differing in theoretical length of cut, with or without cottonseed substituted for alfalfa silage at 27% of alfalfa NDF. The experiment was a replicated (n = 3) 4 x 4 Latin square design with a 2 x 2 factorial arrangement of treatments. Length of cut had no effect on milk production or composition, and substitution of cottonseed increased milk production but did not affect milk composition. An interaction was observed between treatment effects for dry matter intake, total chews per day, and total chewing time (minutes per day). Physical effectiveness of cottonseed NDF was calculated by dividing the total chewing time per unit of cottonseed NDF by total chewing time per unit of alfalfa silage NDF. Physical effectiveness of cottonseed NDF was calculated to be 50% of long-cut and 127% of short-cut alfalfa silage NDF. The interaction observed between main effects for total chewing time per day indicated that the physical effectiveness of whole linted cottonseed was relative and depended on the characteristics of the forage that it replaced.

Relationship between fermentation acid production in the rumen and the requirement for physically effective fiber

The content of ruminally fermented OM in the diet affects the fiber requirement of dairy cattle. Physically effective fiber is the fraction of feed that stimulates chewing activity. Chewing, in turn, stimulates saliva secretion. Bicarbonate and phosphate buffers in saliva neutralize acids produced by fermentation of OM in the rumen. The balance between the production of fermentation acid and buffer secretion is a major determinant of ruminal pH. Low ruminal pH may decrease DMI, fiber digestibility, and microbial yield and thus decrease milk production and increase feed costs. Diets should be formulated to maintain adequate mean ruminal pH, and variation in ruminal pH should be minimized by feeding management. The fraction of OM that is fermented in the rumen varies greatly among diets. This variation affects the amount of fermentation acids produced and directly affects the amount of physically effective fiber that is required to maintain adequate ruminal pH. Acid production in the rumen is due primarily to fermentation of carbohydrates, which represent over 65% of the DM in diets of dairy cows and have the most variable ruminal degradation across diets. The non-fiber carbohydrate content of the diet is often used as a proxy for ruminal fermentability, but this measure is inadequate. Ruminal fermentation of both nonfiber carbohydrate and fiber is extremely variable, and this variability is not related to the nonfiber carbohydrate content of the diet. The interaction of ruminally fermented carbohydrate and physically effective fiber must be considered when diets for dairy cattle are evaluated and formulated.

Esophageal resection for cancer of the esophagus: long-term function and quality of life

BACKGROUND

Information on function and quality of life of long-term survivors after esophageal resection for carcinoma is limited.

METHODS

Between 1972 and 1990, 359 patients underwent esophagectomy for stage I or II esophageal carcinoma at Mayo Clinic. We evaluated long-term function and quality of life in 107 of these patients (81 men and 26 women) who survived 5 or more years. Median age at operation was 62 years (range, 30 to 81 years). The operation performed was an Ivor Lewis resection in 77 patients (72%), transhiatal esophagectomy in 14 (13%), extended esophagectomy in 4 (4%), thoracoabdominal esophagectomy in 4 (4%), and other in 8 (7%). Adenocarcinoma was present in 72 patients (67%), squamous cell carcinoma in 28 (26%), and other in 7 (7%). Thirty-four patients (32%) were in postsurgical stage I, 65 (61%) in stage IIA, and 8 (8%) in stage IIB. Median survival was 10.2 years (range, 5.0 to 23.2 years). Follow-up was complete for all patients.

RESULTS

Gastroesophageal reflux was present in 64 patients (60%), symptoms of dumping in 53 (50%), and dysphagia to solid food in 27 (25%). Seventeen patients (16%) were asymptomatic. Factors affecting late functional outcome were analyzed. Patients who had a cervical anastomosis had significantly fewer reflux symptoms (p < 0.05). Dumping syndrome occurred more frequently in younger patients (p < 0.05) and women (p < 0.01). Quality of life was assessed separately by the Medical Outcomes Study 36-Item Short-Form Health Survey and compared with the national norm. Scores measuring physical functioning were decreased (p < 0.01). Scores measuring ability to work, social interaction, daily activities, emotional dysfunction, perception of health, and levels of energy were similar. Mental health scores were higher (p < 0.05).

CONCLUSIONS

We conclude that long-term functional outcome after esophagectomy for esophageal carcinoma is affected by age, sex, and type of reconstruction. Quality of life as judged by the patients is similar to the national norm.

Treatment of refractory, nonmalignant hydrothorax with a pleurovenous shunt

We present a case of long-term successful application of pleurovenous shunting for the management of pleural effusion. Intractable symptomatic hydrothorax developed as a result of transdiaphragmatic migration of hepatic ascites. After failure of traditional treatment by mechanical pleurodesis, a pleurovenous shunt was inserted. After 1 year of follow-up, the effusion is well controlled, and the shunt remains patent.

A bidirectional load applicator for the investigation of skin response to mechanical stress

Instrumentation was developed to apply controlled biaxial (normal and shear) forces to the skin of a human or animal subject. The instrument mimicked any reference waveform within the constraints of a bandwidth of 15 Hz, a maximum force of 20 N, and displacement ranges of 15 mm for the normal direction and 18 mm for the shear direction. Two shaker motors, positioned with their axes parallel, were used with a low effective mass linkage and small-angle rotational joints to deliver the force. A digital feedback controller independently controlled the instantaneous normal and shear forces and recorded the resultant displacements. Evaluations on human and animal (pig) subjects demonstrated mean absolute errors between the applied and reference waveforms of less than 1.2% full-scale output for both the normal and shear directions. No degradation in performance was apparent over the course of a 1-h loading session. The instrument is to be used for the investigation of skin adaptation to mechanical stress, information that could be used to design new therapeutic methods to encourage skin load-tolerance.

Long-term results after reoperation for failed antireflux procedures

From January 1960 to June 1995, 185 patients underwent reoperation without esophageal resection for symptoms of recurrent gastroesophageal reflux disease. There were 102 men and 83 women. Median age was 58 years (range 20 to 84 years). A single previous antireflux operation had been performed in 147 patients, two in 33, and three in 5. The median interval between the reoperation and the previous operation was 36 months (range 1 to 291 months). Indications for reoperation were symptoms in 184 patients and a large paraesophageal hernia in one patients. The surgical approach was by means of a thoracotomy in 133 patients (71.9%), laparotomy in 27 (14.6%), and a thoracoabdominal incision in 25 (13.5%). A Nissen fundoplication was performed in 107 patients (57.8%), Belsey fundoplication in 47 (25.4%), truncal vagotomy and antrectomy with Roux-en-Y reconstruction in 17 (9.2%), anatomic hernia repair in 12 (6.5%), and Hill gastropexy in 2 (1.1%). A Collis gastroplasty was added to the fundoplication in 116 patients (62.7%), and a pyloroplasty was performed in 17 (9.2%). There was one operative death (0.5%). Complications occurred in 47 patients (25.4%). Median postoperative hospitalization was 9 days (range 5 to 58 days). Follow-up was complete in 156 patients (84.3%) and ranged from 3 to 283 months (median 44 months). Improvement occurred in 137 patients (87.8%). Functional results were classified as excellent in 65 patients (41.6%), good in 29 (18.6%), fair in 43 (27.6%), and poor in 19 (12.2%). No single operative approach or procedure proved to be functionally superior. We conclude that reoperation with esophageal preservation after a failed antireflux procedure will result in significant functional benefit and can be performed with low mortality and acceptable morbidity. The type of repair should be tailored to the individual patient.

Sodium mercaptoacetate is not a useful probe to study the role of fat in regulation of feed intake in dairy cattle

Inhibition of fatty acid oxidation by mercaptoacetate stimulates food intake of rats fed dietary fat. To study regulation of feed intake of ruminants fed fat, dry matter intake and plasma concentrations of insulin and metabolites were determined in eight nonpregnant Holstein heifers in a cross-over design with two 14-d feeding periods by using a 2 x 2 factorial arrangement of treatments. Treatments were combinations of diet (27 or 103 g fatty acids/kg food dry matter) and injection (mercaptoacetate or saline). Half the heifers were fed each diet in Period 1, and diets were reversed in Period 2. On d 10 of each period, two animals per treatment were injected intravenously with either mercaptoacetate (300 mumol/kg body weight 0.75) or saline at 2 h postfeeding. Injections were reversed on d 12. Dry matter intake was suppressed by the high fat diet. Intravenous injection of mercaptoacetate decreased dry matter intake to 25% that of the control during 4 h postinjection. Both the high fat diet and mercaptoacetate injection increased plasma non-esterified fatty acid concentration, whereas plasma beta-hydroxybutyrate concentration was lowered by the high fat diet and by mercaptoacetate injection. Plasma triglyceride concentration was increased by the high fat diet, but was decreased by mercaptoacetate injection. Mercaptoacetate elevated plasma glucose concentrations at 2 and 3 h postinjection, possibly because plasma insulin concentration was lower. Effects of mercaptoacetate on plasma insulin and metabolite concentrations may have been confounded by the effects of decreased feed intake. Therefore, direct effects of mercaptoacetate injection were not separated from effects of feed intake on plasma insulin and metabolite concentration. Because mercaptoacetate injection decreased dry matter intake it was not a useful probe to study mechanisms of feed intake regulation in dairy cattle fed fat.

Malignant fibrous histiocytoma of the lung. Report of four cases and review of the literature

BACKGROUND

Primary malignant fibrous histiocytoma (MFH) of the lung is a rare clinical entity. Only 23 reports of 49 cases have been reported in the literature. Surgery was the primary mode of therapy, with high rates of local and distant recurrence reported. The role of radiation therapy and chemotherapy has never been clearly defined.

METHODS

The records of the Mayo Clinic in Scottsdale and Rochester from 1970 to 1990 were reviewed for cases of primary pulmonary MFH. A review of the literature was also undertaken.

RESULTS

Four cases from the Mayo records and 49 cases from a review of the literature were identified. Eight patients were alive at 5 years from diagnosis; all had been treated with surgery as the primary modality. No definite relationship between histologic subtype of MFH and survival could be identified and no definite role of radiation therapy or chemotherapy could be defined.

CONCLUSIONS

MFH of the lung should be treated by surgical resection if technically feasible. The role of adjuvant therapy remains undefined.

Physical constraints on voluntary intake of forages by ruminants

Voluntary dry matter intake (VDMI) of forages by ruminants may be limited by distention resulting from restricted flow of digesta through the gastrointestinal tract. An animal's capacity for fill depends on the weight and volume of digesta that causes distention and the flow rate of digesta from the organ in which distention occurs. The reticulorumen is generally regarded as the site in the gastrointestinal tract for which distention limits VDMI with high-fill diets, although evidence suggests that distention of the abomasum may also limit VDMI. Linear decreases in VDMI have been noted with increasing amounts of inert fill inserted into the reticulorumen, but results have not been consistent across several experiments. Reduction in VDMI depends on the extent to which intake is limited by fill before insertion of inert fill; hence animals with high energy requirements consuming relatively low-energy, high-fill diets are affected to the greatest extent. Because NDF generally ferments and passes from the reticulorumen more slowly than other dietary constituents, it has a greater filling effect over time than non-fibrous feed components and has been found to be the best single chemical predictor of VDMI. However, many other factors affect fill, including particle size, chewing frequency and effectiveness, particle fragility, indigestible NDF fraction, rate of fermentation of the potentially digestible NDF, and characteristics of reticular contractions. These factors are only partially accounted for in models that have been developed to predict VDMI. Increased accuracy of prediction of VDMI is expected as models continue to evolve.

Diaphragmatic hernia and associated anemia: response to surgical treatment

From 1985 to 1993, 49 patients (35 women and 14 men) with diaphragmatic hernia and associated anemia underwent surgical repair. The median age was 64.5 years (range 24 to 84 years). Hematologic and gastroenterologic evaluations revealed no other potential cause of bleeding. Each patient had a diaphragmatic hernia. The median time between the diagnosis of anemia and surgical repair was 36 months (range 1 to 334 months). Forty-five patients (91.8%) had received replacement therapy, including iron for 43 and blood transfusions for 32 (median 6 units; range 2 to 70 units). Forty-six patients (93.9%) had symptoms: heartburn in 28, early satiety with bloating in 19, regurgitation in 11, dysphagia in 7, and aspiration in 4. Preoperative upper gastrointestinal endoscopic evaluation demonstrated gastric erosions at the level of the hiatus in 22 patients (44.9%), esophagitis in 7, stenosis in 1, and Barrett's disease in 1. An uncut Collis-Nissen fundoplication was performed in 44 patients, Belsey fundoplication in 2, a cut Collis-Nissen fundoplication, Nissen fundoplication, and Hill repair in 1 each. There was one operative death (2% mortality). Complications occurred in 18 patients (36.7%). Follow-up was complete and ranged from 4 to 103 months (median 63 months). Forty-five patients (91.8%) had resolution of their anemia. Functional results were excellent in 40 patients (81.6%), good in 2 (4.1%), fair in 4 (8.2%), and poor in 3 (6.1%). In most patients with diaphragmatic hernia and associated anemia refractory to medical treatment, surgical repair can result in successful resolution of the anemia.

Surgical anatomy of the trachea

A clear understanding of tracheal anatomy is a fundamental building block for surgical procedures. Surprisingly, information about the surgical anatomy of the trachea is scant. This article describes the anatomy of the trachea and highlights how these anatomic facts affect surgical procedures performed on the trachea.

Postoperative chylothorax

Between July 1987 and May 1995, 11,315 patients underwent general thoracic surgical procedures at our institution. In 47 of these patients (0.42%), postoperative chylothorax developed. There were 32 men and 15 women with a median age of 65 years (range 21 to 88 years). Initial operation was for esophageal disease in 27 patients, pulmonary disease in 13, mediastinal mass in six, and thoracic aortic aneurysm in one. All patients were initially treated with hyperalimentation, cessation of oral intake, medium chain triglyceride diet, or a combination. Nonoperative therapy was successful in 13 cases (27.7%), and oral intake was resumed a median of 7 days later (range 2 to 15 days). Reoperation was required in the remaining 34 cases. The reoperation rate varied according to the type of initial operation. Twenty-four of the 27 patients (88.9%) who had undergone an esophageal operation required reoperation, versus only five of 13 patients (38.5%) who had undergone pulmonary resection (p < 0.001). Lymphangiography was performed in 16 patients and identified the site of the leak in 13. The thoracic duct was ligated in 32 of the 34 patients who required reoperation (94%). The remaining two patients were treated with mechanical pleurodesis and fibrin glue. Reoperation was successful in 31 of the 34 patients (91.2%). The single death among the 47 patients (2.1%) occurred in the reoperated group. Complications occurred in 18 patients (38.3%). Factors that predicted the need for reoperation were initial esophageal operation and average daily postoperative drainage greater than 1000 ml/day for 7 days. We conclude that postoperative chylothorax is an infrequent complication. Some cases can be managed without operation; however, we recommend early reoperation when drainage is greater than 1000 ml/day or if the chylous fistula occurs after an esophageal operation. The fistula can usually be controlled by ligation of the thoracic duct.

Surgical management of bronchiectasis

BACKGROUND

The prevalence of bronchiectasis has decreased significantly over recent decades. We reviewed the morbidity, mortality, and outcome of surgical treatment for pulmonary bronchiectasis in the modern era of antibiotic therapy.

METHODS

From January 1976 through January 1993, 134 patients (55 male and 79 female patients) underwent pulmonary resection for bronchiectasis. The mean age was 48.4 years (range, 4 to 89 years). The indication for operation was failure of medical therapy in 85 patients (63.4%), hemoptysis in 26 (19.4%), lung abscess in 12 (9.0%), and a nondiagnostic mass in 11 (8.2%). Mean duration of symptoms was 6 years (range, 1 to 60 years) and included a productive cough in 104 patients, fetid sputum in 91, recurrent infections in 81, and hemoptysis in 56. Thirteen patients (9.7%) had no prior symptoms and presented with either hemoptysis, lung abscess, or unresolved pneumonia. The disease was bilateral in 26 patients (19.4%) and mainly confined to the lower lobe in 75 (56.0%). The mean number of segments involved was 4.4 (range, one to 14 segments). Surgical treatment included lobectomy in 86 patients (64.2%), pneumonectomy in 21 (15.7%), wedge resection or segmentectomy in 18 (13.4%), and a combination of these approaches in 9 (6.7%). Disease was considered completely resected in 108 patients (80.6%).

RESULTS

The operative mortality rate was 2.2% and the morbidity rate was 24.6%. The mean follow-up in 103 patients was 6 years (range, 1 to 16 years). Overall, 61 patients (59.2%) were asymptomatic after operation. Symptoms were improved in 30 patients (29.1%) and unchanged in 12 (11.7%). Complete resection resulted in a significantly better result than incomplete resection (p < 0.05).

CONCLUSIONS

Pulmonary resection for bronchiectasis can be done with low mortality and morbidity. When possible, complete resection should be performed.

Lung resection in patients with compromised pulmonary function

BACKGROUND

Some patients are denied curative pulmonary resection for lung carcinoma because of pulmonary insufficiency. To identify factors that affect postoperative morbidity and mortality, we reviewed 85 consecutive patients (53 men and 32 women) with a preoperative forced expiratory volume in 1 second of less than 1.2 L who underwent pulmonary resection for lung cancer between January 1986 and December 1990.

METHODS

Median age was 70 years (range, 49 to 82 years). Sixty patients (71%) had been previously denied operation because of pulmonary insufficiency. Preoperative pulmonary function demonstrated a median preoperative forced expiratory volume in 1 second of 1.0 L (44% of predicted normal; range, 0.5 to 1.2 L) and a diffusing capacity of the lung for carbon monoxide of 60% of predicted normal (range, 22% to 104%).

RESULTS

Pneumonectomy was done in 6 patients (7.1%), bilobectomy in 6 (7.1%), lobectomy in 38 (44.7%), segmentectomy in 12 (14.1%), and wedge excision in 29 (27.1%). The median predicted postoperative forced expiratory volume in 1 second was 0.83 L (34% of predicted normal; range, 0.45 to 1.14 L), and the median predicted postoperative diffusing capacity of the lung for carbon monoxide was 48% of predicted normal (range, 19% to 87%). Seventy-two patients (85%) received postoperative epidural analgesia. Median hospitalization was 15 days (range, 5 to 66 days). Operative mortality was 2.4%, and complications occurred in 49%. We did not identify any factors that predicted postoperative morbidity and mortality. Median follow-up was 3.2 years (range, 0.2 to 9 years). Seven patients (8%) required supplemental home oxygen. A predicted postoperative percent forced expiratory volume in 1 second less than 43% correlated with the need for home oxygen (p < 0.05). Overall 5-year survival was 44.0%. Survival for stage I cancer was 54.2%; stage II, 33.1%; and stage IIIa, 21.3%.

CONCLUSIONS

We conclude that some patients with lung cancer and compromised pulmonary function can safely undergo pulmonary resection if selected appropriately.