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Biomedical subjects

W R Stewart

Publications and source records attributed to W R Stewart.

At least 19 recordsLinked to original sources
PubMed1994

The effects of psychological stress on the esophagogastric junction pressure and swallow-induced relaxation.

BACKGROUND/AIMS: Short-term psychological stress increases pressure in the upper esophageal sphincter and increases esophageal contraction amplitude. The effects of short-term psychological stress on the two sphincteric mechanisms at the esophagogastric junction (EGJ), the lower esophageal sphincter (LES) and crural diaphragm, were studied. METHODS: Studies were performed in 20 normal, healthy subjects. LES and crural diaphragm functions were measured simultaneously using an electrode sleeve sensor. Three psychological stress tasks, math, cold, and stress interview, were tested. The data were analyzed for tonic (end expiratory) and phasic (inspiratory increase) EGJ pressure and electromyographic changes during the stress period. Spontaneous swallow-induced EGJ relaxation was also assessed. RESULTS: A significant decrease in tonic EGJ pressure occurred during the math and cold tasks. The tonic EGJ pressure was 19 +/- 2 and 14 +/- 2 during baseline and the math task, respectively. Stress caused no change in the phasic EGJ pressures. Tonic and phasic crural diaphragm electromyographic activity increased during all three stress periods. Spontaneous swallow-induced relaxation at the EGJ during the stress periods was reduced from 60% +/- 2% in the baseline to 39% +/- 5% during the stress periods. CONCLUSIONS: Short-term psychological stress lowers EGJ pressure through inhibition of the LES and increases tonic and phasic crural diaphragmatic contraction. Diminished swallow-induced relaxation at the EGJ during stress may lead to changes in esophageal contractions.

Adult↗
PubMed1994

Non-invasive measurement of pulse wave velocity using transputer-based analysis of Doppler flow audio signals.

A system for the measurement of arterial pulse wave velocity is described. A personal computer (PC) plug-in transputer board is used to process the audio signals from two pocket Doppler ultrasound units. The transputer is used to provide a set of bandpass digital filters on two channels. The times of excursion of power through thresholds in each filter are recorded and used to estimate the onset of systolic flow. The system does not require an additional spectrum analyser and can work in real time. The transputer architecture provides for easy integration into any wider physiological measurement system.

Arteries↗
PubMed1994

Paraspinal EMG and autonomic reactivity of patients with back pain and controls to personally relevant stress.

The reactivity of surface paraspinal EMG was contrasted among groups of (1) patients seeking treatment for chronic back pain, (2) nonpatients reporting chronic back pain, and (3) healthy controls. The EMG response to the personally relevant stressor (all stimuli were 1 min.) tasks was greater for the patient group relative to the other two groups. However, the patients' magnitude of response elicited by the control task was nearly equal to that of the personally relevant task, suggesting that the task demand to "describe a recent event" may be the "personally relevant" stressor component rather than the emotional valence attached to the content of that description.

Adult↗
PubMed1992

Effect of a catheter in the pharynx on the frequency of transient lower esophageal sphincter relaxations.

Transient relaxation of the lower esophageal sphincter (LES) is observed fairly frequently during prolonged continuous monitoring of the LES. The aim of this study was to test whether the presence of a catheter in the pharynx through the stimulation of mechanoreceptors may induce transient LES relaxation. LES and esophageal pressure recordings were obtained for 1 hour in six subjects with a manometric catheter placed via a gastrostomy tube. Swallowing was monitored by submental electromyographic recording. Additional recordings were obtained in these subjects with a catheter placed in the pharynx for 1 additional hour. Transient LES relaxations were recorded in both study periods, i.e., with and without a catheter in the pharynx. The frequency of transient LES relaxations was significantly higher in the presence of manometric catheters in the pharynx (6.4 +/- 2.2 vs. 2.0 +/- 1.1 total LES relaxations). The frequency of transient LES relaxation during the first and second hour after placement of the manometric catheter in a group of seven healthy subjects was not significant different. It is concluded that the pharynx is one of the sites that may mediate the induction of transient LES relaxation.

Aged↗
PubMed1991

Abdominal colon and rectal operations in the elderly.

Sixty-seven abdominal operations for colon and rectal disorders were performed on 56 patients 80 years of age or older from January 1, 1984 to June 30, 1989. Nine patients required multiple operations. Sixty-two procedures (92 percent) were performed on patients in their ninth decade; two operations were performed on patients 95 years of age or older. Forty-five patients (80 percent) were operated upon for carcinoma. Operations included segmental colectomy (33 patients), low anterior resection (12 patients), total abdominal colectomy (3 patients) and abdominoperineal resection (2 patients). Forty patients were classified as ASA Class III; the majority were monitored in the surgical intensive care unit for a mean of 2.84 days. Thirty patients were monitored with arterial catheters and 21 with central invasive monitoring. Operative mortality was 7 percent (4 patients). Two patients died from diffuse carcinomatosis; one patient had a fatal myocardial infarction. The final death occurred from multisystem organ failure following anastomotic dehiscence. Twenty-seven operations were performed without postoperative complications; 18 operations were followed by a single minor complication. The average hospital stay was 18.96 days. All patients were admitted from home. Thirty-three returned home postoperatively; 16 were discharged to an extended care facility. In conclusion, elderly patients with colon and rectal disorders can be operated upon with acceptable morbidity and mortality. Age alone should not interdict surgical therapy.

Abdomen↗
PubMed1991

Squamous-cell carcinoma of the anal canal: management with combined chemo-radiation therapy.

Twenty patients with squamous-cell carcinoma of the anal canal received combined chemo-radiation therapy as their primary treatment. There were 18 women and two men with a mean age of 63 years (range, 34-91 years). The mean follow-up was 34 months (range, 6-62 months). Anal margin cancers and adenocarcinomas were excluded. Fourteen of 20 patients treated had a complete response. There were six local failures: three with residual disease at the end of treatment and three with recurrent disease at a later date. Of the three with residual disease, one underwent abdominoperineal resection and two received salvage therapy (one with chemo-radiation and one with radiation alone). All three patients with recurrent disease were treated with abdominoperineal resection. All six were disease free at the end of the study. Of the 14 patients with complete local response, one presented with liver metastases 19 months later. Sixteen patients (80 percent) were alive at the end of the study, and 19 patients (95 percent) had no evidence of disease. These data add support for salvage therapy in the treatment of patients with residual disease following initial chemo-radiation therapy. Salvage options for patients with squamous-cell carcinoma of the anus who fail the Nigro protocol will be discussed.

Adult↗
PubMed1991

Surgical treatment of low rectovaginal fistulas.

Forty women with low rectovaginal fistulas were operated upon over a 9-year period. The etiology of the fistula in the majority was obstetric. Nine women had prior attempts to repair the fistula. All 40 women were managed with endorectal advancement flap with the addition of sphincteroplasty or perineal body reconstruction in 15 patients and rectocele repair in six patients. Postoperative complications included urinary difficulties (two patients) and wound complications (three patients). There were two recurrences. All women treated with sphincteroplasty or perineal body reconstruction were continent. Seven women complained of varying degrees of incontinence postoperatively; none had undergone sphincter or perineal body reconstruction. Endorectal advancement flap is a safe and effective operation for women with rectovaginal fistulas. Concomitant sphincteroplasty or perineal body reconstruction should be performed in women with historical, physical, or manometric evidence of incontinence.

Adult↗
PubMed1991

New directions in the irritable bowel syndrome.

The irritable bowel syndrome (IBS) is an umbrella for the diagnosis of heterogeneous conditions that are awaiting better identification of specific manometric causes. This article focuses on the concept that future therapy for IBS will rely on identification of subgroups and in turn tailor the specific therapeutic approaches to an appreciation of the pathophysiology and symptom predominance of these subgroups. Future therapies will rely on the following principles: (1) prokinetic agents to coordinate upper gastrointestinal and colonic motility as well as improve the propulsive nature of colonic contractions; (2) gastrointestinal hormone agonists such as erythromycin and antagonists such as sandostatin and cholecystokinin antagonists; (3) spasmolytic therapy incorporating calcium channel blocking and anticholinergic agents; (4) inhibition of ovulatory cycle changes in circulating concentrations of gonadal hormones in women, who tend to dominate the IBS population; (5) incorporation of concepts relating to the role of subtypes of 5-hydroxytryptamine receptors in control of neural and myogenic function; (6) reassessment of food intolerance and sensitivity; and (7) incorporation of concepts relating to psychologic profiles and psychologic treatment approaches. IBS is a rich and fertile area for application of the exciting new pharmacologic advances relating to gastrointestinal smooth-muscle and neural innervation of the gut. Improvement in the understanding and treatment of IBS will be one of the major accomplishments of this decade.

Colonic Diseases, Functional↗
PubMed1990

Rectocele repair. Four years' experience.

A retrospective review of 64 rectocele repairs done over a four-year period was performed. The most common indication for repair was constipation. Thirty-five patients were repaired transanally, and 29 were repaired transvaginally. The overall morbidity was 34 percent, and the overall mortality was 0 percent. The most common complication was urinary retention in 12.5 percent. There was no difference in complications between techniques. Of 46 patients contacted for follow-up, 25 (54 percent) still complained of constipation, 17 (34 percent) had partial incontinence, 8 (17 percent) noted persistent rectal pain, 15 (32 percent) mentioned occasional rectal bleeding, and 10 (22 percent) complained of vaginal tightness or sexual dysfunction. Thirty-seven (80 percent) patients stated that they had improved after surgery. Except for persistent rectal pain, there was no difference in results between transanal and transvaginal repairs. Those undergoing transvaginal repair had a much greater problem with pain. Our relatively poor results may be due to an unselective approach to rectocele repair. The presence of both constipation and a rectocele does not imply an association, and a complete anorectal physiologic examination should precede repair. There is no functional difference between transvaginal and transanal rectocele repair.

Adult↗
PubMed1990

Preoperative versus postoperative adjuvant radiotherapy for surgically curable carcinoma of the rectum and distal sigmoid colon.

From January 1979 to October 1986, 86 patients with surgically resectable adenocarcinoma of the rectum or rectosigmoid were treated with adjuvant radiotherapy consisting of preoperative 2,400 cGy (22 patients), preoperative 4,000 cGy (14 patients), "sandwich" technique (27 patients), and postoperative irradiation (23 patients). Average follow-up was 42.9 months. The local recurrence rate was 4.5%, 9.1%, 7.4%, and 34.8%, respectively. The distant metastasis rate was 18.2%, 18.2%, 7.4%, and 30.4%, respectively. Preoperative radiotherapy with adequate surgical resection appears more effective in reducing the incidence of local recurrence.

Adenocarcinoma↗
PubMed1989

Sham feeding. Cephalic-vagal influences on gastric myoelectric activity.

The effects of sham feeding on gastric motility of human subjects have not previously been studied. The amplitude of 3-cpm electrogastrogram (EGG) waves increases after the ingestion of food. We hypothesized that sham feeding would stimulate a similar, but briefer gastric myoelectric response. Healthy human subjects chewed and expectorated a hot dog on a roll and later ate a second hot dog. EGGs were continuously recorded before, during, and after sham feeding and eating. The results of experiment I (N = 27) showed that the hand-scored amplitude of the 3-cpm waves increased significantly (P less than 0.01) during sham feeding. Two minutes after sham feeding, the mean amplitude of 3-cpm EGG waves returned to baseline level. The increase in EGG amplitude during eating was also significant (P less than 0.01), and remained increased for approximately 30 min after ingestion. The procedure used in experiment II (N = 20) was similar to experiment I, but EGGs were computer analyzed and power, ie, spectral intensities, at 3 cpm were obtained. The increase in power at 3 cpm during sham feeding and during eating was significant (P less than 0.05 and P less than 0.02, respectively). Similar to experiment I, the duration of increase in power at 3 cpm was brief during sham feeding compared to the postprandial increase. Four vagotomized subjects failed to show an increase in power at 3 cpm in response to sham feeding. We conclude: (1) The cephalic-vagal stimulation of sham feeding increases briefly the amplitude and power of 3-cpm gastric myoelectric activity in healthy subjects but not vagotomized patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Complete obstruction of the sigmoid colon treated by primary resection and anastomosis--an improved technique (preliminary report). Report of three cases.

Three patients with complete colonic obstruction treated by primary resection and anastomosis with intraoperative colon tube decompression and bowel lumen sterilization without a protective colostomy are presented. An improved colonic decompressor was used. It is postulated that this procedure is an alternative safe technique in patients with colonic obstruction in whom an end-colostomy, mucous fistula, or Hartmann pouch would be necessary.

Aged↗
PubMed1989

Low cost device for removing human and small primate temporal bone plugs.

Previously, only the expensive oscillating saw and Schuknecht temporal trephine were available for removing human temporal bone plugs and no trephines were made for smaller research primates. An inexpensive hole saw has been modified for removing such plugs with an electric drill. This device is less expensive, easier to use, causes less potential impact damage to the plug, and the size of the hole saw can be varied for the size of the skull.

Animals↗
PubMed1989

Gastric emptying and gastric myoelectrical activity in patients with diabetic gastroparesis: effect of long-term domperidone treatment.

We measured gastric emptying and gastric myoelectrical activity with solid-phase gastric-emptying tests and cutaneously recorded electrogastrograms (EGGs), respectively, in six insulin-dependent diabetic patients with nausea and vomiting who did not respond to standard treatments. Baseline solid phase gastric emptying was markedly delayed (78 +/- 8% retained at 120 min) and EGG recordings revealed gastric dysrhythmias; tachygastria (4-9 cpm signals) in one patient, 1- to 2-cpm waves in two patients, and flatline patterns in three patients. No patient had a normal 3-cpm EGG pattern. After 6 months of domperidone treatment, mean upper gastrointestinal symptoms scores decreased from 17.8 to 3.7 (p less than 0.01), and normal 3-cpm EGG frequencies were recorded from each of the six patients. The mean percentage of meal retained at 120 min decreased but did not improve significantly. Thus, establishment of normal 3-cpm gastric myoelectric activity and resolution of dysrhythmias, not normalization of emptying rates, was associated with improvement in upper gastrointestinal symptoms in these diabetic patients.

Adult↗
PubMed1988

A new silicone-prosthesis in the modified Thiersch operation.

Experience with a new silicone prosthesis in the modified Thiersch operation for rectal procidentia in 16 extremely poor-risk patients is presented. The technique of implantation, structural details of the prosthesis, and the clinical results are described. The use of a new silicone prosthesis in the modified Thiersch procedure is a viable alternative in this group of patients. Surgical technique is a primary determining factor in preventing complications.

Humans↗
PubMed1987

Effect of barium meals on gastric electromechanical activity in man. A fluoroscopic-electrogastrographic study.

UNLABELLED: The relationship between the cutaneously recorded electrogastrogram (EGG) and gastric contractions in man is unclear. We investigated: (1) the relationship between the electrogastrogram (EGG) signals and gastric contractions elicited by barium meals and (2) the effects of barium meals on frequency and amplitude of EGG signals. As documented by fluoroscopy in four healthy subjects, barium meals stimulated three per minute gastric peristalsis which corresponded with simultaneously recorded three cycle per minute (cpm) EGG waves. Eighteen other healthy volunteers ingested 45% (w/v) or 60% barium suspensions. As determined by Fourier analysis, the dominant EGG frequency before barium was 3 cpm in 16 subjects; two subjects had no distinct frequency peaks. After barium ingestion, the mean amplitude or power at 3 cpm and 1 cpm increased, but the increase was significant only after 45% barium. IN CONCLUSION: (1) individual EGG waves after barium reflect gastric peristaltic sequences, which are reflected in increases in amplitude or power of 3 cpm EGG activity; (2) density or viscosity of the barium meal affects the gastric myoelectric response; and (3) mechanical correlates of 1 cpm EEG activity are unknown.

Adolescent↗
PubMed1987

The efficacy of barium-enema examinations in patients with anorectal disease.

This retrospective study examines the value of an air contrast barium enema examination in detecting proximal neoplasia in the patient presenting with benign anorectal disease as determined by history, physical examination, rigid, and flexible sigmoidoscopy. In 428 of these patients, the roentgenographic studies showed proximal colonic cancer or polyps in less than 1 percent of patients reviewed. In addition, a review of 402 patients with known colon and rectal cancer were surveyed using the same criteria for diagnosis, and less than 1 percent were misinterpreted as having benign anorectal disease.

Adult↗