PubMed Health⌕ Search

Biomedical subjects

D A Ahlquist

Publications and source records attributed to D A Ahlquist.

At least 73 records · Page 4Linked to original sources
PubMed1988

Mucosal vascular malformations of the gastrointestinal tract: clinical observations and results of endoscopic neodymium: yttrium-aluminum-garnet laser therapy.

Ninety-three consecutive patients with transfusion-dependent gastrointestinal bleeding from vascular malformations (VMs) underwent systematic assessment in our gastrointestinal laser suite with extended upper gastrointestinal endoscopy and colonoscopy. Of these patients, 83 had angiodysplasia and 10 had the Osler-Weber-Rendu (OWR) syndrome. The median age in each of these groups was 70 and 63 years, respectively. Cardiovascular disease, especially valvular disease, was common. A poor correlation existed between the results of endoscopically identified VMs and visceral angiography in patients with angiodysplasia. A combination of upper and lower gastrointestinal VMs was found in 11% of patients with angiodysplasia and 60% of those with the OWR syndrome. All identified VMs were completely obliterated by photocoagulation with use of a neodymium:yttrium-aluminum-garnet (Nd:YAG) laser. Bleeding was successfully controlled in 9 patients with the OWR syndrome and in 72 patients with angiodysplasia (range of follow-up, 1 to 39 months). In 243 laser treatments, 3 perforations and 5 episodes of delayed bleeding occurred. This experience demonstrates that extended upper endoscopy is useful in identifying VMs and that gastrointestinal bleeding from VMs can be safely and successfully controlled with use of endoscopic Nd:YAG laser therapy.

Aged↗
PubMed1988

A stool collection device: the first step in occult blood testing.

Despite widespread fecal blood testing, the technique of gathering stool for sampling has remained uncontrolled. We sought to describe how patients have contended with this awkward step, to study artifact caused by toilet water, and to construct a collection device that prevents sampling problems. A survey of 250 patients showed that most (56%) had retrieved stools from the toilet basin, 17% used a pan or other household receptacle, 10% used newspaper or tissue paper, and 17% had been unable or unwilling. Sampling stool from the toilet basin introduces error because 4% to 75% of blood leaches from the fecal surface into surrounding water after only 4 to 12 minutes, and many toilet sanitizers cause false-positive guaiac reactions. We describe an inexpensive, disposable stool collector; outpatient compliance has been 97% using this device. To avoid biochemical artifact and facilitate stool sampling, we advocate that a collection device be incorporated into the occult blood testing process.

Adult↗
PubMed1987

Influence of aspirin and ethanol on fecal blood levels as determined by using the HemoQuant assay.

We sought to determine the short-term effects of use of aspirin and ethanol on fecal occult blood levels measured with the HemoQuant assay. A factorial design was used to study 68 healthy volunteers randomized to receive various doses of aspirin, ethanol, or a combination of both for either 1 or 3 days. Fecal hemoglobin concentrations were measured before and after drug ingestions. Moderate quantities of ethanol (300 ml of 5% or 30 ml of 50% three times nightly) did not cause significant fecal blood elevation unless aspirin was administered concomitantly (P = 0.05). High-dose aspirin alone, 975 mg three times daily, induced abnormal blood loss (P less than 0.01). The highest HemoQuant levels were usually noted after concomitant administration of aspirin and ethanol at maximal doses for 3 days (P less than 0.005), some HemoQuant levels approaching 5 times the normal value. We conclude that, in a short-term analysis, social consumption of ethanol is unlikely to interfere with fecal blood testing but therapeutic doses of aspirin will.

Adult↗
PubMed1987

Endoscopic laser palliation of malignant dysphagia: a prospective study.

We prospectively studied the short-term and long-term efficacy and safety of endoscopic laser treatment in 25 patients with dysphagia from advanced esophageal cancer. Malignant stenoses were recanalized in all patients, and the ability to swallow was improved in about 80%. Results were best in patients with adenocarcinomas and in those who reported a good appetite. A single laser treatment provided adequate palliation in more than half the patients until the time of death. In those patients in whom stenosis recurred, re-treatment was necessary a median of 3.2 months after the initial laser treatment. No laser-related mortality or major morbidity occurred. We conclude that endoscopic laser therapy seems to be a feasible method of palliating malignant dysphagia.

Adenocarcinoma↗
PubMed1986

Defects in prostaglandin synthesis and metabolism in ulcer disease.

Ulcers occur because of an imbalance between mucosal protective resistance and damaging luminal factors, allowing the latter to predominate. The primary injurious elements are acid and peptic activity. Bile reflux, drugs, and gastroduodenal stasis may alter the luminal milieu and act together with acid-peptic activity to produce injury, weaken mucosal resistance, or both. Since prostaglandins modulate several key mucosal protective mechanisms, and since some exogenous prostaglandins and their derivatives accelerate peptic ulcer healing, it seems plausible that prostaglandin deficiency may contribute to the development of peptic ulcers. At the present time, however, evidence for this postulate is mostly indirect and can be summarized as follows: (1) Defects of mucosal protective mechanisms modulated by prostaglandins have been found in different forms of ulcer disease. Such defects include impaired duodenal bicarbonate secretion, deficient secretion or accelerated degradation of mucus, and reduced mucosal cell proliferation. (2) Drugs that inhibit cyclooxygenase, the key enzyme in tissue prostaglandin synthesis, have ulcerogenic activity. Presumably, in this situation, reduced prostaglandin production renders the mucosa more vulnerable to the action of acid and pepsin, or reduces the capability of the mucosa to repair itself. (3) Decreased mucosal prostaglandin synthesis or prostaglandin content has been found in patients with ulcer disease. Several studies have provided quantitative evidence of disturbed prostaglandin metabolism in some forms of ulcer disease. These studies are of high interest, but they need to be interpreted with caution given the present scientific debate regarding the physiological role of different prostanoids, as well as uncertainty as to the specific cellular source of prostaglandins in gastroduodenal mucosa.

Animals↗
PubMed1986

Laser therapy for severe radiation-induced rectal bleeding.

Four patients with chronic hematochezia and transfusion-dependent anemia from postradiation rectal vascular lesions were successfully managed by endoscopic laser coagulation. In all four patients, symptomatic, hematologic, and endoscopic improvement was evident. Laser therapy for severe radiation-induced rectal bleeding seems to be safe and efficacious and should be considered before surgical intervention.

Aged↗
PubMed1985

Fecal blood levels in health and disease. A study using HemoQuant.

We tested HemoQuant, a quantitative assay of fecal blood based on the fluorescence of heme-derived porphyrin, in 106 healthy volunteers, 170 patients with gastrointestinal symptoms but with normal diagnostic studies, 44 patients with gastrointestinal cancer, 75 patients with benign polyps, and 374 patients with a variety of other benign gastrointestinal lesions, including ulcers and erosions. In 98 per cent of the healthy volunteers, fecal hemoglobin concentrations were less than 2 mg per gram of stool. Levels were similarly low in stools from patients with symptoms and normal studies and in patients with relatively minor benign lesions. Within these groups, levels were slightly higher in those who had ingested red meat or aspirin. The fecal hemoglobin concentration was higher in patients with gastrointestinal cancer than in any other group, and 97 per cent of those with colorectal cancer had levels above 2 mg per gram. The sensitivity of HemoQuant was significantly greater than that of the guaiac test Hemoccult, particularly when heme was degraded or stools were dry. Intestinal degradation of heme to porphyrin can be measured separately by HemoQuant, and was greater when bleeding was from proximal lesions rather than distal ones. We conclude that HemoQuant is a more sensitive measure of gastrointestinal bleeding than Hemoccult, and that its capacity to measure degraded heme may be useful in indicating the anatomic site of bleeding.

Evaluation Studies as Topic↗
PubMed1984

Gastrointestinal blood loss and anemia in runners.

Iron deficiency, with or without anemia, occurs commonly in long-distance runners, but the cause is unknown. The recent development of a simple quantitative assay for fecal hemoglobin, HemoQuant , allowed us to study whether gastrointestinal bleeding occurs in runners. Blood and stool samples were collected from 24 runners before and after a race of 10 to 42.2 km and from age- and sex-matched, nonrunning controls. The mean blood hemoglobin level and hematocrit were significantly lower in runners than in controls. Serum ferritin levels were below normal in 4 runners but in no controls. Fecal hemoglobin levels increased in 20 of 24 runners (p less than 0.01) after a race. Mean fecal hemoglobin level was 1.08 mg/g (range, 0.11 to 2.36) in controls and 0.99 mg/g (0.18 to 2.41) in runners before a race, but peaked at 3.96 mg/g (0.37 to 43.20) after a race. Competitive long-distance running induces gastrointestinal blood loss and may contribute to iron deficiency.

Adult↗
PubMed1984

HemoQuant, a new quantitative assay for fecal hemoglobin. Comparison with Hemoccult.

HemoQuant, an assay based on heme-derived porphyrin, quantifies both total fecal hemoglobin ant that fraction already converted to porphyrin by gut flora (the intestinal converted fraction). Recovery by HemoQuant of blood added to stools exceeded 99% and was not affected by ascorbic acid, iron, or other additives. HemoQuant was used to evaluate the performance of Hemoccult on 1018 stools. Hemoccult sensitivity differed widely, remaining negative with up to 42.5 mg hemoglobin per gram of stool (about 43 mL/d of blood) but positive with only 0.04 mg of hemoglobin per gram of stool. Driest stools tended to be Hemoccult-negative and the wettest Hemoccult-positive. Hemoccult-negative stools became positive after aqueous dilution independent of hemoglobin concentration. The intestinal converted fraction, not detected by guaiac tests, often constituted most of the fecal hemoglobin equivalents and was significantly higher in Hemoccult-negative than in Hemoccult-positive stools. Hemoccult lost reactivity during fecal storage due to progressive heme degradation. Frequent false-negative and false-positive reactions of Hemoccult were explained largely by variations in stool liquidity and heme degradation.

Diagnostic Errors↗
PubMed1983

Factors influencing metabolism of arachidonic acid in guinea pig gastric mucosa.

The metabolism of [14C]arachidonic acid in whole homogenates of gastric corpus mucosa in the guinea pig was characterized. Identity of labeled products was validated by comigration against standards in multiple chromatographic systems and by selective synthesis inhibition. At near-physiological conditions, homogenates converted arachidonic acid to the cyclooxygenase products prostaglandins F2, E2, and D2, 6-keto-prostaglandin F1 alpha, and thromboxane B2 (in descending order of magnitude) and to a lipoxygenase product cochromatographing with 12-hydroxyeicosatetraenoic acid. However, dramatic qualitative and quantitative changes in this product profile were noted with relatively small changes in incubation temperature, substrate concentration, and especially pH. Whole homogenates generated more prostaglandin and in different proportions than did the microsomal fraction from an equal mass of mucosa. No catabolism of prostaglandin products was observed in whole homogenates. Tissue preparation and storage also influenced prostaglandin synthesis activity. These in vitro observations may have important implications for future studies of prostaglandin generation in small gastric mucosal biopsies.

6-Ketoprostaglandin F1 alpha↗
PubMed1983

Duodenal prostaglandin synthesis and acid load in health and in duodenal ulcer disease.

We sought to test the hypothesis that duodenal ulcer disease results from an imbalance between duodenal acid load, an injurious force, and mucosal prostaglandin generation, a protective factor. Ten patients with duodenal ulcer and 8 healthy controls were studied. The duodenal acid load after an amino acid soup was quantified by a double-marker technique. Mucosal biopsy specimens were taken endoscopically from the duodenal bulb before and after the test meal. Prostaglandin synthesis activity was measured by incubating biopsy homogenates in excess [14C]arachidonic acid. Although mean duodenal acid load was higher in duodenal ulcer, ranges overlapped. Neither the qualitative nor quantitative profile of mucosal prostaglandin synthesis activities differed significantly between test groups. Prostaglandin synthesis activities, however, tended to increase post cibum in controls, but change little or decrease in duodenal ulcer. Only by comparing the responses with a meal of both parameters together (duodenal acid load and the change in prostaglandin synthesis activities) was there complete or nearly complete separation of duodenal ulcer from controls. Greatest discrimination was observed with prostacyclin (6-keto-PGF1 alpha). We conclude that in health, mucosal prostaglandin generation in the duodenum is induced post cibum in relation to duodenal acid load; this may be a physiologic example of adaptive cytoprotection. In duodenal ulcer there may be a defect in such a mechanism.

Adult↗
PubMed1982

Prostaglandin generation from gastroduodenal mucosa: regional and species differences.

Regional and species differences in prostaglandin synthesis from gastroduodenal mucosa were assessed radiometrically. In the presence of excess added arachidonic acid substrate, corporal mucosa generated more prostanoid product per DNA than did antral or duodenal mucosa whether the whole homogenate or the microsomal fraction was used as an enzyme source. This appeared to be secondary to variability in cyclooxygenase activity and could not be explained by regional differences in the activity of enzymes competing for arachidonic acid substrate, in free endogenous arachidonic acid levels, in prostaglandin catabolizing activity, or in homogenate inhibitors. The qualitative product profile differed between species but not between regions within a species.

Animals↗
PubMed1980

Pseudoinsulinoma syndrome from inadvertent tolazamide ingestion.

A 70-year-old woman with rheumatoid arthritis presented with fasting hypoglycemia, inappropriately elevated insulin and C-peptide levels, and negative insulin antibodies, all compatible with the diagnosis of an insulinoma. However, results of a 72-hour fast were subsequently negative. Medication identification revealed that the patient had been taking tolazamide (Tolinase; The Upjohn Company, Kalamazoo, Michigan) instead of tolmetin (Tolectin; McNeil Laboratories, Inc., Fort Washington, Pennsylvania).

Adenoma, Islet Cell↗
PubMed1975

Use of leuco-dyes in the quantitative colorimetric microdetermination of hemoglobin and other heme compounds.

Sensitivity, stability, and specificity of the color-producing reaction of hydrogen peroxide with bezidine, leuco-malachite green, or o-dianisidine were tested in numerous systems containing hemoglobin and other hemoproteins. Use of urea or low temperature (to minus 12 degrees C), or both, was highly beneficial, especially with leuco-malachite green, for which the color reaction was stable, after about 15 min, for longer than 24 h, with a colorless bank. Absorbance was 0.3 at a final hemoglobin concentration of 0.27 mg/liter. Nonspecific color produced by substances such as FeCl-3 and ascorbic acid was completely eliminated. Of the three leuco-dyes studied, only benzidine yielded a completely linear calibration curve, but its relative instability and reported carcinogenicity are serious disadvantages. No system tested eliminated completely the known inhibition by plasma of the peroxidase activity of these leuco dyes.

Colorimetry↗
PubMedDate not supplied

Prospective comparison of contact with noncontact Nd:Yag laser therapy for palliation of esophageal carcinoma.

Twenty patients with dysphagia due to inoperable esophageal cancer were randomized to receive either contact or noncontact endoscopic laser treatment. Treatment groups were similar with respect to age, dysphagia score, and tumor dimensions. The median number of initial treatment sessions was two in both groups, and the median treatment times per session were 23 min (range, 12 to 55 min) in the contact group and 19 min (range, 5 to 28 min) in the noncontact group. Median dysphagia scores were also similar in both groups 1 month after laser treatment, and no difference was apparent in the duration of palliation. There were no patient complications attributable to laser therapy, but damage to the laser wave guide occurred in three contact sessions and two noncontact sessions. These data suggest no advantage for the contact method of endoscopic Nd:YAG laser palliation of esophageal carcinoma with respect to number of treatment sessions, relief of dysphagia, or occurrence of complications.

Adenocarcinoma↗