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Biomedical subjects

L M Nyhus

Publications and source records attributed to L M Nyhus.

At least 19 recordsLinked to original sources

Evolution of hernia repair: a salute to Professor Piero Pietri.

This subject has been well covered in recent years. Yet it seems appropriate to search for major advances in hernia methodology during the last 100 years. Eduardo Bassini is credited with pioneering the modern era. His "triple layer" repair was corrupted through the years and, as a result, he did not receive sufficient credit for his attention to the posterior inguinal wall. Chester McVay, renowned surgeon-anatomist, renewed interest in the Cooper's ligament and the posterior inguinal wall. Surgeons from the Universities of Washington and Illinois perfected approaches to the posterior inguinal wall. Thus, these investigators paved the way for several effective posterior hernia operations. The name of Usher will forever be remembered in terms of practical prosthetic mesh (polypropylene). This material, as well as others, has become an important addition to the surgeon's armamentarium. Rene Stoppa reminded us of the Pascal principle and clearly demonstrated how giant prostheses can remain in the preperitoneal space without the need for sutures. Tension-free operations, plug techniques, and laparoscopic hernia methodology must await further analysis.

Eponyms↗

Creation, evaluation, and continuing assurance of excellence of the certified surgical specialist.

A position paper on the subject of certified surgical specialists was published in 1966 under the direction of Professor Charles Wells of Liverpool, England. President John Terblanche of the International Federation of Surgical Colleges brought together leaders in surgical education from four nations (Australia, Japan, South Africa, United States) to update current "state-of-the art" views. Presentations were made at the 38th Congress of the International Society of Surgery, August 18, 1999 in Vienna, Austria. After careful review of the four presentations, it was clear that surgeons all over the world have made great improvements in the many facets of surgical education. Yet the advances remain spotty, with gaps noted when viewed from an international perspective.

Australia↗

Marked asymmetry of LES: important element of LES barrier in subsets of patients with reflux symptoms.

Computerized axial manometry (CAM) of the lower esophagus measures squeeze pressure at multiple points in each segment of the lower esophageal sphincter (LES), calculates several unique parameters of LES function, and constructs a 3-D display of the LES. Whether parameters derived from CAM, such as the radial mean pressure (LESrmp), Asymmetry (Asym), and Vector Volume (VV), have relevance to function of the LES remains undefined. This study compares the results of CAM in patients with gastroesophageal reflux disease (GERD) and controls. There were 54 patients with GERD and 21 volunteers; all underwent CAM as part of their evaluation; GERD was defined by clinical and endoscopic examinations, and all patients had abnormal 24-hour pH tests. Statistical evaluation was performed. The LESrmp and the Vector Volume were significantly correlated in both groups of patients and differed significantly in both. Asymmetry of the LES was a significant negative factor in LES strength as shown by VV and LESrmp. Asymmetry alone, however, did not show a strong correlation with reflux. Asymmetry is indirectly correlated with the major determinants of LES strength; in patients with low VV, asymmetry might be a critical factor. When a high VV is present, asymmetry has no particular relevance. CAM provides invaluable measurements of the LES.

Analysis of Variance↗

Esophagocardiomyotomy--floppy Nissen fundoplication effectively treats achalasia without causing esophageal obstruction.

BACKGROUND: Effective surgical treatments for achalasia of the esophagus facilitate swallowing by division of muscles that fail to relax normally during swallowing. If esophagocardiomyotomy is performed, a complementary antireflux procedure is mandatory to prevent postoperative gastroesophageal reflux. We evaluated patients who had undergone a circumferential antireflux procedure after esophagocardiomyotomy to determine the effects of this procedure in patients with an aperistaltic esophagus. METHODS: During the past 15 years we treated 94 patients with achalasia by use of pneumatic dilation (66), esophageal myotomy (19), or esophagocardiomyotomy with floppy Nissen fundoplication (24). Achalasia was defined by radiographic and manometric criteria until 1986 when computerized axial manometry of the esophagus was initiated, providing information about the three-dimensional contour and "volume" of the lower esophageal sphincter in addition to the usual manometric data. RESULTS: Dysphagia was effectively relieved in all, and neither postoperative reflux nor esophageal obstruction was observed after esophagocardiomyotomy followed by floppy Nissen fundoplication. The measured lower esophageal sphincter pressures and sphincter volume were markedly reduced. CONCLUSIONS: Esophagocardiomyotomy with floppy Nissen fundoplication is an effective treatment for achalasia; clinical evidence of obstruction of the esophagus was not seen, and manometric data were typical of a weakened sphincter.

Cardia↗

[Extended superselective vagotomy. Experimental bases and application in the surgical treatment of duodenal ulcer].

There is a sound basis for performing EHSV with reference to the "areas of vagotomy" as described and for wider application of EHSV. Most patients with complications of duodenal ulcer disease can be treated successfully by EHSV, with a small incidence of recurrent ulcers. The liberal use of pyloroplasty or drainage procedures is justified, since the potential problems of perioperative infection and postoperative alkaline reflux are not clinically significant. Post-gastrectomy syndromes can be largely avoided if gastric resection is reserved only for the few patients with deep ulcers of the lesser curvature. Intraoperative testing for completeness of vagotomy is a useful adjunct in the performance of EHSV, especially by those who are learning the technique. If the principles of EHSV are followed, routine use of intraoperative testing is superflous.

Drainage↗

The ipsilateral organization of the afferent nerves to the stomach.

In previous nerve tracing studies we found evidence that the efferent gastric vagus nerves supplying the anterior gastric wall had a regional organization. The first part of this study aimed to determine whether vagus afferent nerve cells supplying the stomach have a regional organization; an ipsilateral pattern of innervation was found. Next, selective blockade of the afferent nerves was performed and verified by axonal tracing. Animals with afferent blockade were stressed to determine the effect of afferent nerve blockade on the gastric stress response. After selective blockade of afferent vagus nerves to the anterior gastric wall in rats, water-immersion stress was then applied. The part of the gastric wall with afferent nerve blockade had fewer acute gastric lesions than control animals or the contralateral side of the stomach after 24 hr of stress. This study supports the hypothesis that afferent as well as efferent vagus nerves have an ipsilateral arrangement. Afferent nerve blockade of the left vagus nerve protected the anterior wall of the stomach against stress ulceration.

Afferent Pathways↗

Effects of afferent and efferent celiac nerves on acute gastric lesions: due to changes in blood flow?

Since ablation of afferent nerves prior to stress results in increased severity of acute gastric mucosal lesions, afferent nerves are thought to mediate protective mechanisms in the stomach. These mechanisms are known to include vasodilation of gastric mucosal vessels; vasodilation is thought to allow the gastric mucosa to respond to injurious substances. However, it is not known whether other aspects of mucosal health, independent of those caused by increased blood blow, are affected by afferent blockade. This study compared gastric blood flow and acute gastric mucosal lesions during stress in rats with either chemical sympathectomy or afferent blockade. The purpose of the study was to compare the lesion index and blood flow in each treatment group. The lesion index was highest in rats with afferent blockade and lowest after sympathectomy. Gastric blood flow was partially preserved after sympathectomy, but was not greatly increased, suggesting that some of the effects observed after afferent blockade are unrelated to changes in blood flow.

Animals↗

Experimental basis and clinical application of extended highly selective vagotomy for duodenal ulcer.

An ideal operation for a benign disease, such as duodenal ulcer, must be effective, relatively free of serious postoperative complications and standardized for effective performance. Highly selective vagotomy, an operation known to have few side effects, has not been adopted by many surgeons because of the concerns about postoperative recurrent ulcers, as well as by concerns about the technical performance of the operation. Recurrent ulcers may be the result of incomplete denervation of the parietal cell mass; based upon the results of intraoperative testing, we suspected that previously unrecognized sites supplied preganglionic vagus nerves to the parietal cell mass. Nerve tracing studies identified four areas in the stomach that are not adequately denervated in the "standard" highly selective vagotomy. Based on these data, we defined and performed "extended highly selective vagotomy" upon 180 patients with ulcers. Herein, the results of follow-up examinations of 113 patients for a mean of at least 4.5 years postoperatively are reported. Recurrent duodenal ulcers occurred in 2.9 percent (two of 69) after extended vagotomy alone, and in none of 44 in whom a drainage procedure was used; the overall recurrence rate was 1.8 percent. Serious postoperative complaints were found in one patient in each group. The use of extended highly selective vagotomy for duodenal ulcer has a rational experimental basis and acceptable clinical results. Pyloroplasty, in conjunction with extended highly selective vagotomy, does not increase the incidence of serious postoperative side effects.

Duodenal Ulcer↗

Inhibition of afferent vagus nerves decreases gastric stress lesions.

Capsaicin (Sigma Chemical Co.) is a unique chemical agent that causes degeneration of afferent nerve fibers. Previous conclusions about Capsaicin effects on the gastric mucosal response to stress have not precisely defined which afferent nerves were affected. Therefore, the aim of the first portion of this study was to define the origin of afferent vagus nerves to the anterior gastric wall after injections of fluorogold (which is an axonal tracer) into the stomach. The second part of this study was to compare the stress effects on the gastric mucosa in rats with impaired afferent nerve function after Capsaicin treatment.

Acute Disease↗

Response of brain protein kinase C isozymes to ethyl oleate, an alcohol metabolite.

Rat brain protein kinase C (PKC) isozymes I, II and III were stimulated by fatty acids in the absence and presence of calcium. Ethyl oleate, which by itself has no effect on PKC activity, had a potentiating effect on fatty acid-induced activation of all 3 isozymes. Potentiation was observed predominantly in the presence of calcium. Interaction of ethyl oleate with a signalling mechanism involving PKC may underlie the cognitive disturbances noted after alcohol consumption.

Animals↗