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Biomedical subjects

M S Allen

Publications and source records attributed to M S Allen.

At least 109 records · Page 6Linked to original sources
PubMed1995

Prediction of protein degradation of forages from solubility fractions.

Two experiments were conducted to determine the relationship between enzymatic digestion of forage protein and fractionation based on solubility. The first experiment used 42 forages, each replicated three times, including different species, stages of maturity, and methods of conservation. Crude protein was fractionated into six parts for each forage by sequential extraction in TCA, bicarbonate-phosphate buffer, acetone, detergent at pH 7, and detergent with acid. Multiple regression analysis, with all the solubility fractions as independent variables, resulted in prediction of CP degradation by ruminal enzyme extract at 2 and 24 h; R2 were .88 and .81, respectively. Greater solubility in the buffer and the detergent at pH 7 was associated with higher protein degradation; solubility in acetone, detergent with acid, and insolubility were associated with lower degradation. In the second experiment, eight forages each replicated twice were digested with ruminal enzyme for 0, 2, 6, and 24 h and then were extracted as described. Solubility in TCA and acetone increased during degradation, but solubility in buffer, detergent with acid, and insolubility decreased. For both experiments, buffer-soluble CP was the only uniform fraction across forages; other fractions contained proteins that degraded at diverse rates. Solubility of CP is related to degradation properties, but further research is needed to improve the accuracy of predictions based on solubility.

Animal Feed↗
PubMed1995

Pharyngoesophageal diverticulum: technique of repair.

Pharyngoesophageal diverticulum is an acquired defect resulting from an incoordination of the cricopharyngeal muscle. Common symptoms are dysphagia, regurgitation, and aspiration. The defect is repaired through a cervical incision and should include a diverticulectomy and a myotomy. Results are excellent and complications are unusual.

Aged↗
PubMed1994

Evolving strategies in lung transplantation for emphysema.

Evolving strategies of pulmonary preservation, bronchial revascularization, immunosuppression, and infectious disease management were used in 15 initial consecutive patients undergoing lung transplantation for emphysema. There were 10 women and 5 men with a mean age of 49 years (range, 36 to 60 years). All patients required supplemental oxygen therapy. One bilateral, 9 left, and 5 right transplantations were performed. Mean preoperative forced expiratory volume in 1 second and total lung capacity were 16% and 146%, respectively, of predicted. Quadruple drug immunosuppression was used. Actuarial 1-year survival in this initial series is 93.3% +/- 6.4% (Kaplan-Meier) with one early cardiac death at day 71. Mean forced expiratory volume in 1 second and diffusing capacity for carbon monoxide at discharge were 43% and 62%, respectively, of predicted. Rehabilitation has been excellent, and all survivors are active and free of supplemental oxygen. During the study, the following treatment strategies have evolved: (1) University of Wisconsin solution has replaced Euro-Collins' solution for pulmonary preservation; (2) direct bronchial revascularization with the internal thoracic artery now is used; (3) an algorithm-based variable dose OKT3 induction regimen has resulted in a major reduction in dosage; and (4) infectious disease management focuses on the prophylaxis of cytomegalovirus and fungal infection using prolonged ganciclovir and early itraconazole therapy as well as the avoidance of Epstein-Barr virus mismatches. Single-lung transplantation for emphysema has excellent early results with continuing evolving management strategies.

Adenosine↗
PubMed1994

Pulmonary resection of metastatic renal cell carcinoma.

Between 1965 and 1989, 96 consecutive patients (64 men and 32 women) underwent complete pulmonary resection for metastatic renal cell carcinoma. Median age was 63 years (range, 33 to 82 years). Median time between nephrectomy and pulmonary resection was 3.4 years (range, 0 to 18.4 years). Forty-eight patients had solitary metastasis, 16 had two, 18 had three, and 14 had more than three. Wedge excision was performed in 62 patients, segmentectomy in 3, lobectomy in 25, bilobectomy in 3, and pneumonectomy in 3. Fourteen patients had repeat thoracotomy for recurrent metastasis; 34 other patients also had complete resection of limited extrapulmonary disease. There were no operative deaths. Median follow-up was 3 years (range, 70 days to 19.0 years). Overall 5-year survival was 35.9%. Patients with solitary metastasis had a 5-year survival of 45.6% compared with 27.0% for patients with multiple metastases (p < 0.05). Patients with a tumor-free interval greater than the median of 3.4 years had a better survival (p = 0.05) than those with a tumor-free interval less than or equal to 3.4 years. Five-year survival for patients who underwent repeat thoracotomy or had complete resection of extrapulmonary disease did not differ from overall survival. We conclude that resection of renal lung metastasis is safe and effective, that patients with solitary metastasis have a better survival than those with multiple metastases, that resectable extrapulmonary disease does not necessarily contra-indicate pulmonary resection, and that repeat thoracotomy is warranted in selected patients with recurrent lung metastases.

Adult↗
PubMed1994

Results of surgical resection in patients with N2 non-small cell lung cancer.

From January 1982 to December 1986, 167 patients (121 men and 46 women) with non-small cell lung cancer and a clinically negative mediastinum were found to have N2 lymph node metastases at thoracotomy and underwent pulmonary resection. Ages ranged from 31 to 86 years (median, 66 years). Adenocarcinoma was present in 70 patients (41.9%), squamous cell carcinoma in 64 (38.3%), large cell carcinoma in 20 (12.0%), adenosquamous cell carcinoma in 7 (4.2%), and bronchoalveolar cell carcinoma in 6 (3.6%). Forty-seven patients (28.1%) underwent mediastinoscopy; all results were negative. Pneumonectomy was performed in 64 patients, bilobectomy in 4, lobectomy in 76, segmentectomy in 2, and wedge excision in 21. Twenty patients had an incomplete resection. Thirty-five patients (21.0%) had complications, and the operative mortality was 4.8% (8 of 167 patients). Sixty-seven patients (40.1%) received adjuvant radiation therapy. The 5-year survival for the 147 patients who underwent complete resection was 23.7%. In contrast, 19 of the 20 patients (95.0%) who underwent incomplete resection died within 3 years. Other factors that significantly affected the 5-year survival were the number and location of metastatic lymph node stations, age, type of resection, and whether adjuvant radiation therapy was administered. We conclude that, when N2 disease is found at thoracotomy, complete resection is warranted to achieve long-term survival.

Adult↗
PubMed1994

Pulmonary resection for metastatic breast cancer.

Between 1982 and 1992, 60 consecutive female patients underwent pulmonary resection for metastatic breast carcinoma. Median age was 58 years (range, 21 to 81 years). The median tumor-free interval after primary breast cancer operation was 2.2 years (range, 7 days to 20.6 years). Thirty-one patients (51.6%) had solitary pulmonary metastases. Forty patients (66.7%) had complete pulmonary resection, which consisted of wedge excision in 33, lobectomy in 6, and pneumonectomy in 1. The remaining 20 patients had incomplete resection, which consisted of wedge excision in all. Altogether, 8 patients (13.3%) had development of postoperative complications, which included pneumothorax, prolonged air leak, pulmonary embolism, retained secretions requiring bronchoscopy, atrial fibrillation, and chest tube site infection. There was one operative death (1.7%). Follow-up was complete in all patients and ranged from 23 days to 10.7 years (median, 3.5 years). Recurrence developed in 32 of the 39 survivors (82.1%) who had complete resection. Median disease-free interval after lung resection was 1.6 years (range, 23 days to 9.3 years). Overall 5-year survival was 37.8% (95% confidence interval, 25.1% to 50.5%). The 40 patients who had complete resection had a 5-year survival of 35.6% (95% confidence interval, 20.4% to 50.8%) as compared with 42.1% (95% confidence interval, 19.0% to 65.3%) for the 20 patients with incomplete resection (p = not significant). Although pulmonary resection is safe, we could not demonstrate improved survival after complete pulmonary resection of metastatic breast carcinoma in this highly selected group of patients.

Adult↗
PubMed1994

Lipothymoma with red cell aplasia, hypogammaglobulinemia, and lichen planus.

We describe a patient who had lipothymoma with red cell aplasia, hypogammaglobulinemia, and lichen planus. Parathymic syndromes described in association with lipothymomas also include myasthenia gravis, hyperthyroidism, lymphangioma, aplastic anemia, chronic lymphocytic leukemia, and Hodgkin's disease. The behavior of lipothymoma is generally benign, although local recurrence was noted in 1 patient who had an incomplete resection. Lipothymoma should be considered in the diagnosis of mediastinal tumors and parathymic syndromes, and also in patients with cardiomegaly, phrenic nerve palsy, and a widened mediastinum.

Adult↗
PubMed1994

Variation in and relationships among feeding, chewing, and drinking variables for lactating dairy cows.

Twelve Holstein cows (63 DIM; 6 primiparous) were offered a common diet and monitored for 21 d (11 d of adaptation, 10 d of collection) with a data acquisition system to measure continuously feed and water intakes and chewing behavior. Objectives were to examine relationships among feeding behavior variables for noncompeting cows producing various quantities of milk and to determine experimental designs with adequate power to detect reasonable treatment differences in future experiments. Coefficients of variation across cows ranged from 5 to 41% for the variables studied. Milk production was correlated positively with DMI and water intake within and across parities. For multiparous cows, production was related positively to meal size (r = .78) and length of eating bouts (r = .75) and unrelated to meal number and eating rate. For primiparous cows, production tended to be related positively to meal number (r = .55) and eating rate (r = .87) and unrelated to meal size. Rumination and total time spent chewing per unit of DMI were correlated negatively (r = -.58) with milk production within and across parities. These correlations suggest that differences exist among cows for chewing efficiency. Reasons why high producing cows consume and chew more effectively deserve further study. Contrast differences of 10% of means for variables examined had an 80% probability of detection with a Latin square design utilizing 12 cows monitored for 5 d.

Animals↗
PubMed1994

Empyema following pulmonary resection.

Empyema after lung resection is an uncommon, but serious, complication. Its reported incidence varies from 1% to 5%, and it is frequently associated with a bronchopleural fistula. This article covers the prevention and treatment of empyema. Treatment requires the use of appropriate antibiotics, adequate drainage, obliteration of the pleural space, and closure of the fistula in order to achieve a long-term successful outcome.

Bronchial Fistula↗
PubMed1994

Extended esophagectomy in the management of carcinoma of the upper thoracic esophagus.

Upper thoracic esophageal tumors adjacent to the trachea often require a preliminary thoracotomy to accomplish resection. Between January 1985 and July 1992, 49 consecutive patients (38 men and 11 women) underwent extended esophagectomy for esophageal cancer where the neoplasm was mobilized through an initial right thoracotomy and then resected and reconstructed through an abdomino-cervical approach. Ages ranged from 40 to 80 years (median 63.4 years). The tumor was located in the upper third of the thoracic esophagus in 44 patients and in the middle third in five. Thirty-three patients had squamous cell carcinoma, 14 had adenocarcinoma, and two had adenosquamous cell carcinoma. Complications occurred in 35 patients (71.4%) and included anastomotic leak in 15, vocal cord paralysis in 11, atrial arrhythmia in nine, pneumonia in six, wound infection in five, and postoperative bleeding in one. Three patients required tracheostomy. There was one postoperative death (2.0%). Median survival was 0.9 years (range 1 month to 5.1 years). Thirty-one patients were alive at the time this article was written, 28 without evidence of cancer. Cause of death was recurrent disease in 13 patients, unrelated to cancer in three, and unknown in one. Overall actuarial 3- and 5-year survivals were 48.6% and 18.2%, respectively. Four-year survival for stage II disease was 44.6% as compared to 24.9% for stage III (p < 0.02). The presence of lymph node metastases significantly affected survival. Three-year survival for patients with N0 disease was 77.9% compared with 20.9% for patients with N1 disease (p < 0.01). Age, sex, and cell type had no effect on survival. Ten patients had late dysphagia, four had gastroesophageal reflux, and one had dumping symptoms. Although associated with significant morbidity, we conclude that extended esophagectomy is an acceptable method of management for tumors of the upper thoracic esophagus. Mortality is low, and long-term results are reasonable.

Adenocarcinoma↗
PubMed1993

Epiphrenic diverticulum: results of surgical treatment.

From 1975 to 1991, 112 patients (64 men and 48 women) were found to have an epiphrenic diverticulum. Symptoms were absent or minimal in 71 patients and incapacitating in 41. All patients with minimal symptoms were managed conservatively; 35 were available for follow-up, which ranged from 1 to 25 years (median, 9 years). None of these 35 patients had clinically significant progression of symptoms. Surgical repair was done in 33 patients with incapacitating symptoms. Achalasia was present in 8 of the surgical patients (24.2%), diffuse esophageal spasm in 3 (9.1%), hypertensive lower esophageal sphincter alone in 1 (3.0%), and nonspecific motor abnormalities of the esophageal body in 7 (21.2%). Diverticulectomy and esophagomyotomy were performed in 22 patients, diverticulectomy alone in 7, esophageal resection in 3, and esophagomyotomy alone in 1. Concomitant hiatal hernia repair was done in 6 patients. Complications occurred in 11 patients; 6 had esophageal leaks. There were three operative deaths (9.1%), all occurring in patients with abnormal manometry. Follow-up was complete in 29 patients and ranged from 4 months to 15 years (median, 6.9 years). Long-term results were excellent in 14 patients (48.2%), good in 8 (27.6%), fair in 5 (17.2%), and poor in 2 (6.9%). We conclude that operation has significant risks and is not warranted in patients with minimal symptoms because progression is unlikely. Surgical treatment, however, is advisable in patients with incapacitating symptoms because most operative survivors will have long-term symptomatic palliation.

Adult↗
PubMed1993

Transhiatal esophagectomy for carcinoma of the esophagus.

One hundred thirty-one patients (107 men and 24 women) underwent transhiatal esophagectomy for carcinoma of the esophagus. Median age was 65.3 years (range, 30 to 89 years). Signs and symptoms were present in 130 patients, which included dysphagia in 96 (73.3%) and weight loss (median, 7.7 kg) in 52 (39.7%). The cancer involved the gastroesophageal junction in 94 patients, the lower half of the intrathoracic esophagus in 25, the upper half in 10, and multiple sites in 2. An adenocarcinoma was present in 101 patients (77.1%), squamous cell carcinoma in 29 (22.1%), and adenosquamous cell in 1 (0.8%). The cancer was classified as stage 0 in 4 patients, stage I in 16, stage IIA in 26, stage IIB in 18, stage III in 65, and stage IV in 1. The stomach was used to replace the esophagus in all patients. Operative mortality was 2.3%. Anastomotic leak developed in 32 patients; 6 leaks were not clinically significant, 12 healed with drainage alone, and 14 required further surgical intervention. Follow-up ranged from 1 month to 6.7 years (median, 1.4 years). Currently, 42 patients are alive, 34 without evidence of recurrence. Overall 5-year survival was 20.8% and varied according to stage. Five-year survival was 47.5% for patients with stage I disease compared with 37.7% for patients in stage II and only 5.8% 4-year survival for patients in stage III. Cell type also influenced survival. Five-year survival for patients with adenocarcinoma was 27.1% compared with zero for patients with squamous cell carcinoma (p < 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1993

Equipment for thoracoscopy.

The combining of miniaturized video technology with thoracoscopy now allows surgeons to perform a variety of thoracic procedures percutaneously. Both rigid and flexible video thoracoscopes are available. The rigid endoscope has a camera located proximally at the eye-piece and is capable of excellent resolution. However, visualization of the entire pleural cavity is difficult because of the rigid chest wall. Placing the video camera at the distal end of a flexible thoracoscope, as in the electronic video thoracoscope (EVE-L; Fujinon, Wayne, NJ), yields better visualization of these relatively inaccessible areas. However, disadvantages of the flexible thoracoscope include increased expense and complexity, reduced resolution as compared to rigid systems, and the need for a strobed light source, thus making video-assisted surgery more difficult. Thoracoscopic wedge excisions of the lung are now possible because of the adaptation of gastrointestinal staplers for percutaneous use. The initial design consisted of a reloadable 30-mm disposable stapler. Newer models, however, have a longer staple line and some are reusable. Future refinements may allow the head of the instrument to articulate, thus permitting it to be applied to the lung at various angles. Thoracoscopic ports that provide an air-tight seal are available but are not essential; therefore, standard thoracotomy instruments can be utilized through small open incisions. Specialized disposable thoracoscopic instruments are also available, including scissors, dissectors, and fan retractors. It is hoped that the future will bring improved optics, better staplers, and refined percutaneous instrumentation.

Humans↗
PubMed1993

Pulmonary arteriovenous malformations: therapeutic options.

We have treated 21 patients (13 female, 8 male) with pulmonary arteriovenous malformations (PAVMs). Mean age at diagnosis was 37.5 years (range, 15 to 72 years). Presenting symptoms included dyspnea on exertion (67%), hereditary hemorrhagic telangiectasia (57%), and major neurologic events (33%). In our early experience, 8 patients had no specific treatment; their case histories illustrate the major neurologic complications of untreated PAVMs. Nine patients (8 primarily, 1 after recurrence) underwent conservative surgical excision; 4 had lobectomy, and 5 had segmentectomy or subsegmental excision. One patient underwent staged bilateral thoracotomies for multiple bilateral lesions. The arterial oxygen tension was found to increase after excision of large or solitary PAVMs. All surgically treated patients were relieved of dyspnea, and none had postoperative recurrence of PAVMs or neurologic complications related to PAVMs. Five patients underwent balloon occlusion of PAVMs. Two patients chose to have solitary PAVMs occluded rather than undergo thoracotomy. One underwent surgical excision 5 years later, and the other required repeat balloon embolization 4 years later when recanalization of the PAVMs was documented. Three patients with numerous PAVMs received palliation with multiple balloon embolizations. The high incidence of associated major neurologic complications mandates aggressive treatment of PAVMs whenever feasible. Conservative surgical resection remains the treatment of choice. Balloon embolization offers an alternative therapy for patients who are poor surgical risks or those whose lesions are too numerous to resect.

Adolescent↗
PubMed1993

Barrett's disease: pathophysiology of metaplasia and adenocarcinoma.

Peptic ulceration arising in the lower esophagus lined by columnar epithelium was described in detail by Tileston in 1906. Although this concept was challenged in 1950 by Barrett, experimental and clinical evidence has now conclusively demonstrated that Barrett's metaplasia is an acquired condition and is a consequence of chronic reflux of gastric or duodenal contents or both. Current concepts suggest that unknown trophic factors present in these secretions stimulate proliferation of multipotential reserve cells located in the esophageal submucosal glands resulting in columnar metaplasia of the normal squamous epithelium with subsequent potential for malignant degeneration. Today, numerous patients are affected by reflux esophagitis, a lesser number by Barrett's metaplasia, and a smaller but ever-enlarging group by adenocarcinoma. Although high-grade dysplasia is considered a precursor to invasive adenocarcinoma, detection of this abnormal mucosa remains controversial and currently requires esophagoscopy with biopsy. Epithelial markers, such as increased activity of mucosal ornithine decarboxylase, sulfomucin production, nuclear DNA aneuploidy, and recently molecular analysis, have also been proposed to identify those paitents at increased risk for malignant degeneration. As more is learned about the pathogenesis of Barrett's disease, perhaps these cancers can ultimately be prevented.

Adenocarcinoma↗
PubMed1993

Rare pulmonary neoplasms.

We reviewed the clinical course and the results of various treatment modalities of 80 patients with rare pulmonary neoplasms, who constituted 0.8% of all patients with primary lung cancer treated at the Mayo Clinic from 1980 through 1990. The 50 male and 30 female patients had a median age of 60 years (range, 20 to 87). The histopathologic types of these rare pulmonary neoplasms were non-Hodgkin's lymphoma (41%), carcinosarcoma (20%), mucoepidermoid carcinoma (15%), malignant fibrous histiocytoma (5%), malignant melanoma (4%), fibrosarcoma (4%), leiomyosarcoma (4%), angiosarcoma (2%), hemangiopericytoma (2%), osteosarcoma (1%), and blastoma (1%). Follow-up was complete in all 80 patients, and the median duration of follow-up was 59 months (range, 15 to 130). Of the 80 patients, 63 (79%) underwent pulmonary resection. Of the other 17 patients, 8 underwent only bronchoscopy for diagnosis, 4 had unresectable disease at thoracotomy, 3 had metastatic disease on initial assessment, and 2 had mediastinal involvement detected on mediastinoscopy. Fifty-four patients (68%) received chemotherapy or radiation treatment (or both). The overall 5-year survival was 39%. The strongest factors that influenced survival were cell type and extent of disease at time of initial examination.

Adult↗
PubMed1993

Malignant tracheal tumors.

Malignant tracheal tumors are uncommon and present diagnostic and therapeutic challenges. The most frequently diagnosed types of such tumors are squamous cell and adenoid cystic carcinomas. These tumors usually manifest with the obstructive symptom of wheezing; thus, they are often misdiagnosed as asthma. Rigid bronchoscopy is the best procedure for determining a definitive diagnosis. The recommended treatment is primary resection and reconstruction of the trachea when possible. If the lesion is too extensive, radiation therapy, bronchoscopic "coring out" of the tumor, laser treatment, or internal stenting may provide palliation. Surgical resection necessitates experience with complex airway procedures and can be done with minimal morbidity. The long-term prognosis depends on the histologic type and the size of the tumor; excellent results can be achieved with early diagnosis and appropriate surgical treatment.

Carcinoma↗