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Biomedical subjects

W C Wu

Publications and source records attributed to W C Wu.

At least 109 records · Page 6Linked to original sources
PubMed1990

Comparison of lower esophageal sphincter manometrics and gastroesophageal reflux measured by 24-hour pH recording.

We compared lower esophageal sphincter (LES) pressures to parameters of acid reflux measured during 24-h pH monitoring in 81 patients being evaluated for possible reflux disease. Mid-respiratory LES pressures were significantly higher (p less than 0.05) in patients with normal amounts of reflux than in those with abnormal reflux. This difference did not occur with LES pressure measured by end-expiratory station pull-through (SPT) or rapid pull-through (RPT). There was no significant difference in total length or intra-abdominal portion of LES between the two groups. However, the product of LES pressure and total LES length was greater (p less than 0.05) for patients with normal reflux than for these with abnormal reflux. No difference was noted in the percentage of abnormal contractions in the distal esophagus between groups. These studies support the following conclusions: 1) LES pressure may be a more important protective mechanism against reflux than LES length. 2) Mid-respiratory SPT technique appears to identify the LES antireflux barrier better than either end-expiratory SPT or RPT techniques. 3) Acid exposure time seems to be a better measure of gastroesophageal reflux than the number of reflux episodes.

Esophagogastric Junction↗
PubMed1990

A simple method for maintaining Xanthomonas campestris pv. citri.

A typical colony of each of strains XW17, XW45, XW47, XW82, XW86, XW118, and XW138 of Xanthomonas campestris pv. citri was streaked onto nutrient agar, GY agar, minimal agar, and semi-enriched minimal agar plates, respectively. The agar plates, after incubated at 30 degrees C for 2-4 days, were inverted and stored at 4 degrees C in darkness. All of the X. campestris pv. citri strains retained their viability for at least 26 weeks on the semi-enriched minimal agar plates; whereas, cultures of these bacterial strains survived for only 2-10 weeks on the nutrient agar, 2-5 weeks on the GY agar plates and 12-26 weeks on the minimal agar plates. The bacterial strains which survived after 22-26 weeks on the semi-enriched minimal agar and minimal agar plates, respectively, also retained their ability to produce typical colonies and virulence. Thus, this semi-enriched minimal agar plate method is a simple and efficient way for maintaining the X. campestris pv. citri strains for a relatively long period.

Culture Media↗
PubMed1989

Does sleeping on a waterbed promote gastroesophageal reflux?

We conducted a randomized prospective study with extended intraesophageal pH monitoring on two consecutive nights to test the hypothesis that a waterbed (WB) might increase recumbent acid exposure compared to a regular bed (RB). We studied 10 controls (mean age 29 years; five males, five females) with no history of reflux symptoms more than two times per month. We also studied 10 reflux patients (mean age 42 years; seven males, three females) with symptoms at least five days a week and documented recumbent reflux, with or without upright reflux, by previous 24 hr pH study. A standard meal (56% fat) was provided at 6 PM. After randomization, the subjects and patients slept on the assigned bed (WB or RB) in one nearby hotel. The pH probe was removed the next morning at 8 AM. On the same day, the pH probe was inserted at 4 PM and the routine was repeated with use of the other bed. No significant difference (P greater than 0.05; paired t test) was found between the regular bed and waterbed in any measurement of recumbent reflux. Our study does not support the hypothesis that greater recumbent reflux may occur when sleeping flat on a waterbed compared to a regular bed. It does not, however, absolutely refute the possible association of waterbed use with esophagitis, since elevation of the head of a waterbed is not possible.

Beds↗
PubMed1989

Endoscopic biopsy is diagnostic in gastric antral vascular ectasia. The "watermelon stomach".

Gastric antral vascular ectasia was endoscopically diagnosed in seven patients. Pathologic characteristics of this entity were defined retrospectively, by studying endoscopic pinch biopsy slides from these seven patients and antrectomy specimens from five patients. A scoring system was developed, and the seven patients were compared prospectively with various control groups. Abnormalities of mucosal vessels (fibrin thrombi and/or ectasia) consistently distinguished patients from control antrectomies, normal biopsies, acute gastritis biopsies and atrophic gastritis biopsies (P = 0.02, all comparisons). Spindle cell proliferation into mucosa also was characteristic of gastric antral vascular ectasia, distinguishing this disease from normals, acute gastritis, and atrophic gastritis (P less than or equal to 0.039, each comparison). The presence of abnormal mucosal vessels (fibrin thrombi and/or ectasia) and spindle cell proliferation was similar in patient antrectomies compared to patient endoscopic biopsies. Therefore, we conclude that endoscopic biopsies can reliably diagnose gastric antral vascular ectasia, a vascular disorder characterized by abnormal mucosal vessels and spindle cell proliferation.

Aged↗
PubMed1989

Radiographic and manometric correlation in achalasia with apparent relaxation of the lower esophageal sphincter.

We compared the clinical, radiographic, and manometric findings in 10 patients with atypical achalasia showing complete lower esophageal sphincter (LES) relaxation to 39 patients with classic achalasia (i.e., incomplete LES relaxation). Those with atypical achalasia were younger (46.1 vs 60.6 years), had dysphagia of shorter duration (18.7 vs 45.7 mos), had lost less weight (8.2 vs 21.5 lbs), and had less esophageal dilatation (2.8 vs 3.9 cm). However, the mean LES pressures (34.5 vs 37.7 mmHg) and the esophagogastric junction calibers (4.5 vs 4.8 mm) were similar. Radionuclide esophageal emptying studies were done in 15 patients (6 with atypical achalasia; 9 with classic achalasia) and were abnormal in all. Most patients in both groups (90 and 92%) responded well to pneumatic dilatation. We conclude that achalasia with apparent LES relaxation may represent an early form of this motor disorder and that the radiographic findings remain characteristic except for less dilatation of the esophagus.

Adult↗
PubMed1989

Prostaglandins in the gut and their relationship to non-steroidal anti-inflammatory drugs.

Prostaglandins are long-chain, saturated, oxygenated fatty acids. Relatively large quantities of prostaglandins have been found in gut mucosa, suggesting that these substances play an important role in gastrointestinal physiology. Non-steroidal anti-inflammatory drugs (NSAIDs) cause damage to the gastric, intestinal, and colonic mucosa in experimental animals and in humans. Prostaglandins protect the gastric mucosa against injury induced by NSAIDs, and this property has been labelled cytoprotection. The mechanisms of cytoprotection have been extensively evaluated and are probably multifactorial, including effects on the gastric mucosal barrier, gastric blood flow, mucus, bicarbonate, and fluid section, ionic transport, cyclic AMP, and surface-active phospholipids. Prostaglandins may also prevent NSAID-induced injury in the small intestine and colon. The mechanisms responsible for prostaglandin protection in the lower gut against injurious agents are unknown. Further studies of the role of prostaglandins in the gut and their relationship to the effects of NSAIDs are needed. The results of these investigations may lead to a better understanding of the importance of prostaglandins in the physiology of the gastrointestinal tract, and may provide information regarding actions of NSAIDs on the functional integrity of the gastric, intestinal, and colonic mucosa.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1989

Introduction of impermeant molecules into synaptosomes using freeze/thaw permeabilization.

Brief freezing as a means of transiently permeabilizing synaptosomes was explored. Rat brain synaptosomes frozen and thawed in the presence of 5% dimethyl sulfoxide, a cryoprotectant, were shown to release, in a calcium-dependent manner, previously accumulated [3H]norepinephrine and [14C]acetylcholine in response to elevated [K+]. In addition, synaptosomes subjected to freeze/thaw were shown to retain their ability to exhibit resting protein phosphorylation, as well as stimulated protein phosphorylation occurring in response to calcium influx. Brief freezing of synaptosomes in the presence of [gamma-32P]ATP and either the catalytic subunit of cyclic AMP-dependent protein kinase or calcium/calmodulin-dependent protein kinase II rendered the synaptosomal interior accessible to these agents, as reflected by the phosphorylation of substrate proteins, such as synapsin I, which reside within the nerve terminal. Inclusion of inhibitors of these protein kinases during freeze/thaw blocked synaptosomal protein phosphorylation, indicating that the inhibitors were also introduced. After freezing, the synaptosomes resealed rapidly and spontaneously, as shown by the inability of any of the agents to elicit an effect on phosphorylation when added at the end of the freezing period. The permeabilization procedure should contribute to an understanding of the functional roles of phosphoproteins, and of their associated protein kinases and protein phosphatases, in nerve terminals.

Acetylcholine↗
PubMed1989

Acid perfusion test: does it have a role in the assessment of non cardiac chest pain?

Using 24 hour pH monitoring as a reference standard, the usefulness of the acid perfusion (AP) test in predicting gastro-oesophageal reflux disease (GORD) was assessed in 71 non-cardiac chest pain (NCCP) patients and 23 endoscopic oesophagitis patients. Of the 71 NCCP patients, 35 had a positive AP test (of whom 20 had an abnormal 24 hour pH) and 36 had a negative AP test (of whom 14 had an abnormal 24 hour pH study). Thus, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the AP test in this group was 59%, 59%, 57%, and 61%, respectively. The corresponding values in the oesophagitis group were 85%, 67%, 94%, and 40%. In the NCCP group when heartburn alone was used as the positive criterion the PPV rose to 74%. When chest pain with or without heartburn was used, however, the PPV dropped to 38%. A 'symptom index' was used to define the number of chest pain episodes that were caused by acid reflux. Only 48% of AP test positive patients had demonstrable acid mediated chest pain. In the NCCP population with a normal oesophageal examination (1) AP test reproduction of chest pain is poorly predictive of GORD; (2) AP test reproduction of heartburn is more predictive of GORD but does not ensure that the chest pain is caused by GORD; (3) a negative AP test does not exclude GORD and (4) only 48% of AP test positive patients have demonstrable acid mediated chest pain. The ambulatory 24 hour pH test may have rendered the AP test obsolete in the assessment of GORD as the cause of NCCP.

Adult↗
PubMed1989

Diffuse esophageal spasm: radiographic and manometric correlation.

Diffuse esophageal spasm (DES) is characterized by substernal chest pain, dysphagia, and a manometric pattern of frequent simultaneous contractions with intermittently normal peristalsis. The authors correlated the radiographic and manometric findings in 17 patients with DES to better clarify the role of radiography in the evaluation of this uncommon motility disorder. Incomplete or absent primary peristalsis was observed on radiographs in 13 patients (76%), and mild to severe tertiary activity was seen in 12 patients (71%). The mean estimated thickness of the esophageal wall in patients with DES was 2.6 mm compared with 2.5 mm in an age-matched control group of 17 patients with normal esophageal manometric findings (P greater than .05). The authors conclude that most patients with DES show abnormal esophageal motility on radiographs, although the findings were nonspecific and required clinical and manometric correlation. Esophageal wall thickness was normal in patients with DES and appears to be an overemphasized sign in differentiating DES from other esophageal motility disorders.

Adult↗
PubMed1989

Esophageal motility: assessment with synchronous video tape fluoroscopy and manometry.

Synchronous video tape fluoroscopy and manometry of the esophagus was performed in 11 subjects (seven men and four women; mean age, 49 years). Four had normal and seven had abnormal esophageal motility (diffuse esophageal spasm, n = 4; nonspecific esophageal motility disorder, n = 3) that was shown by previous manometry. A digital timer appeared on the video tape recording and marked the manometric tracing synchronously. Alternate 5-mL and 10-mL barium boluses were recorded for a total of 10 swallows per patient. Video tape examinations were reviewed prospectively, and the status of primary peristalsis and presence and severity of tertiary activity were noted. A total of 98 swallows (58 normal, 40 abnormal) were correlated, and a 96% agreement was found in assessing primary peristalsis. Overall results of fluoroscopic examinations of each subject during all swallows showed complete agreement with those of manometry; segregating the swallows into groups of five showed 92% concordance. Severe tertiary activity was invariably seen with abnormal primary peristalsis at fluoroscopy.

Barium Sulfate↗
PubMed1989

Positive predictive value and posttest probability of diagnosis of colonic polyp on single- and double-contrast barium enema.

The positive predictive value for a radiographic diagnosis of colonic polyp, the prevalence of polypoid disease, and posttest probability relative to patient age were studied. The positive predictive value for colonic polyp on single- and double-contrast barium enema was determined for 191 polyps found radiographically in 136 patients who also underwent colonoscopy for confirmation. Of 72 polyps seen in 54 patients on single-contrast examination, 59 were confirmed endoscopically; 110 of 119 polyps seen in 82 patients on double-contrast examination were confirmed similarly, giving positive predictive values of 82% and 92%, respectively. Positive predictive values per patient, disregarding the number of polyps present, were 87% (47/54) and 90% (74/82) for the single- and double-contrast examinations, respectively. False-positive errors were due to stool, air bubbles, haustration, and misinterpretation of an appendiceal stump. By using specificities derived from our prevalence of polypoid disease and previously reported sensitivities, we drew posttest probability curves showing that predictive values depend both on the chance of disease before the test is done and on the efficacy of the test used.

Aged↗
PubMed1989

Chronic hoarseness secondary to gastroesophageal reflux disease: documentation with 24-h ambulatory pH monitoring.

Gastroesophageal reflux (GER) has been implicated in otolaryngologic problems, particularly chronic hoarseness that cannot be attributed to other causes. To study this relationship, we used 24-h ambulatory intraesophageal or dual pharyngoesophageal pH monitoring in 33 patients with chronic hoarseness and laryngeal lesions suggestive of acid irritation. Twenty-six of the patients (78.8%) had pH evidence of severe GER, being at least three times greater than the upper limit of normal. In contrast to 19 patients with proven esophagitis, this GER was worse in the upright position. Of 15 patients with both pharyngeal and esophageal probes, three had esophagopharyngeal reflux, and two had atypical unexplained pharyngeal decreases in pH to below 4.0. Less than half of the 33 patients had the typical symptoms of GER, and standard esophageal tests usually yielded normal findings. Occult GER, predominantly in the upright position, appears to be common and severe in patients with chronic hoarseness, who have laryngeal lesions suggestive of GER. The causative mechanisms are not clear. The 24-h esophageal pH monitor is useful in screening this potentially treatable problem.

Adult↗
PubMed1989

Barium enema examination: sensitivity in detecting colonic polyps and carcinomas.

We analyzed the sensitivity of the barium enema examination in 128 patients with 191 endoscopically proven colonic polyps and 12 carcinomas, relative to patient age, indications, and the type of examination used. Seventy-seven patients (60%) had rectal bleeding, and 51 (40%) patients with 87 lesions, including six carcinomas, did not. Overall roentgenographic sensitivity was 88%, with a 93% detection rate in patients less than 70 years old as compared to 76% for older patients. Sensitivity of single- and double-contrast barium enema examination was 82% and 91%, respectively. There were similar detection rates for lesions 1 cm or more in size (91% vs 95% for single- and double-contrast examinations, respectively), but double-contrast examination was slightly better at detecting smaller polyps (88%, vs 70% for single-contrast examination). Compared to colonoscopy, which has an average reported false-negative rate of 12% in detecting neoplasms, the barium enema is similarly reliable, less costly, and safer.

Adult↗
PubMed1989

A comparison of high and low fat meals on postprandial esophageal acid exposure.

Fatty foods have been identified as precipitating factors in symptomatic gastroesophageal reflux (GER). A fat meal has also been found to decrease lower esophageal sphincter pressure (LESP) in normal subjects. We used the ambulatory 24-h pH monitor to assess esophageal acid exposure in 10 normal subjects and 10 GER patients following low and high fat meals eaten in two body positions. The meals had nearly identical protein content, volumes, and calories. On successive days, patients ingested one of the meals twice, followed by random assignment to 3 h upright and 3 h recumbent position. Acid exposure for each hour over a 3-h postprandial (PP) period was assessed as the percent time pH less than 4.0. Increased upright acid exposure occurred in normals after the high fat (6.2 +/- 2.1%; mean +/- SE) compared with the low fat meal (1.5 +/- 0.5%; p less than 0.05). GER patients had greater (p less than 0.05) acid exposure than normals in all study periods, but no differences were found between low and high fat meals in either study position. High fat meals induce upright GER in normals, but do not significantly affect the abnormal amount of GER in patients. In addition, progressive increases in acid exposure were found over the 3 postprandial hours in GER patients in a recumbent position. The findings are consistent with prior data showing decreased LESP with a fat meal in normals.

Adult↗
PubMed1988

Acid-induced esophagitis in cats is prevented by sucralfate but not synthetic prostaglandin E.

The cytoprotective effects of liquid sucralfate and a synthetic analog of prostaglandin E1 (PGE1) on acid-induced esophagitis in cats were studied. Esophagitis was induced in adult cats using a constant infusion of 0.1 N HCl at 1 ml/min for 20 min. Animals were infused for either one or three days. Mucosal lesions were evaluated by blinded investigators using both fiberoptic endoscopy and light microscopy. Histologic changes included basal cell hyperplasia, intraepithelial leukocytosis, and subepithelial leukocytosis. Liquid sucralfate given prior to acid infusion consistently prevented acid-induced lesions in both one- and three-day infusions, demonstrated by both endoscopy and quantitative histologic scoring. Indomethacin (200 micrograms/kg) given prior to sucralfate and acid did not affect sucralfate cytoprotection. Synthetic PGE1, given in doses of 5 micrograms/kg and 100 micrograms/kg, afforded no esophageal cytoprotection. These studies indicate that sucralfate is cytoprotective against acid-induced esophageal injury in cats, an effect that does not appear to be mediated by prostaglandin. In addition, synthetic PGE1 does not confer protection in this animal model.

Animals↗