Search PubMed⌕ Search

Biomedical subjects

D A Ahlquist

Publications and source records attributed to D A Ahlquist.

At least 55 records · Page 3Linked to original sources
PubMed1993

Accuracy of fecal occult blood screening for colorectal neoplasia. A prospective study using Hemoccult and HemoQuant tests.

OBJECTIVES: To define the validity of fecal blood as a marker for colorectal neoplasia in the screening setting and to compare yields by Hemoccult and HemoQuant fecal occult blood screening tests. DESIGN: A multicenter masked comparison of fecal blood test results against structural colorectal evaluations and longitudinal follow-up, serving as criterion standards, in nonreferred subjects at risk for colorectal neoplasia. SETTING: Communities, primary care centers, referral centers. PARTICIPANTS: Two groups: (1) 1217 patients aged at least 18 years undergoing routine structural surveillance evaluations following curative resection of a colorectal tumor and (2) 12312 relatives of colorectal cancer patients aged at least 50 years. INTERVENTIONS: Blinded Hemoccult II and HemoQuant testing on three mailed-in stool samples per subject. MAIN OUTCOME MEASURE: Sensitivity of fecal blood tests for colorectal neoplasia. RESULTS: In the postresection group, surveillance evaluations revealed 46 malignant colorectal neoplasms and 402 polyps. At matched specificity, sensitivity of either test for cancer was 26% (95% confidence interval, 13% to 39%). Hemoccult was positive in 21% of intraluminal recurrences, 33% of all new primary tumors, and 29% of Dukes A or B cancers; HemoQuant was elevated in 24%, 28%, and 29%, respectively. Sensitivity for polyps 1.0 cm or larger was 13% by Hemoccult and 11% by HemoQuant. In the group of relatives, estimated sensitivity for cancer at 1 to 3 years of follow-up was 25% to 33% by Hemoccult, not significantly different from the 29% to 43% by HemoQuant. CONCLUSIONS: Based on our observations in the screening setting, fecal blood appears to be a poor marker for colorectal neoplasia. Most cancers and the vast majority of polyps will be missed. Hemoccult and HemoQuant are similarly insensitive.

Adult↗
PubMed1993

Endoscopic laser coagulation of radiation-induced mucosal vascular lesions in the upper gastrointestinal tract and proximal colon.

UNLABELLED: Endoscopic laser coagulation effectively controls bleeding from radiation-induced rectal vascular lesions. OBJECTIVE: To assess the outcome of endoscopic treatment of radiation-induced bleeding due to vascular lesions located proximal to the sigmoid colon. METHODS: We identified 15 consecutive patients with such proximal radiation enteropathy treated at our Institution with Nd:YAG laser between 1984 and 1991. Ten patients (66%) had gastric and/or small bowel involvement, and five (33%) had colonic involvement with or without more proximal lesions. Bleeding first appeared at a mean of 21.2 +/- 12.5 months after completion of radiotherapy. Mean duration of gastrointestinal bleeding before laser treatment was 7.6 +/- 4.6 months. RESULTS: After completion of laser therapy, bleeding ceased in nine (60%) patients, decreased in three (20%), and persisted in three (20%). The mean hemoglobin level increased from 8.4 +/- 0.5 g/dl to 10.4 +/- 0.6 g/dl after completion of laser treatments (p < 0.02). The mean number of transfusions per patient per year decreased from 10.5 +/- 2.8 to 0.9 +/- 0.7 (p < 0.01). No treatment-related complications or deaths occurred. CONCLUSIONS: Endoscopic laser coagulation of radiation-induced mucosal vascular lesions in the upper gastrointestinal tract and proximal colon appears to be safe and, in most cases, effective.

Colonic Diseases↗
PubMed1992

Long-term nonsteroidal anti-inflammatory drug use and gastroduodenal injury: the role of Helicobacter pylori.

To evaluate the association of Helicobacter pylori infection with gastroduodenal ulceration and symptoms in rheumatoid arthritis patients chronically ingesting nonsteroidal anti-inflammatory drugs (NSAIDs), a population-based study was performed. Residents of Olmsted County, Minnesota, and surrounding counties, 40 years of age and over with active rheumatoid arthritis taking therapeutic dose of NSAIDs daily for 6 months or more were evaluated (n = 50). An endoscopic score from 0 to 5 was assigned and independently confirmed. Biopsies were obtained from the antrum and gastric body for the presence of H. pylori. A symptom score based on the frequency and severity of dyspeptic symptoms was calculated. Substantial mucosal injury (greater than or equal to grade 2) was observed at endoscopy in 33 patients (66%); 14 (28%) had chronic ulcers. Eleven of the community patients with rheumatoid arthritis (22%) were H. pylori positive; adjusting for age, the prevalence of H. pylori was not significantly different to that in 67 health controls (25%). One or more upper gastrointestinal symptoms were reported by 19 of the community patients (38%). Adjusting for age, community rheumatoid arthritis patients with H. pylori were not more likely to have visible mucosal damage or dyspepsia, but were significantly more likely to have histological gastritis (P less than 0.01). The results suggest that, in primarily asymptomatic persons from the community with rheumatoid arthritis taking daily NSAIDs for 6 months or more, H. pylori infection is not related to the severity of visible mucosal injury.

Adult↗
PubMed1992

Possible role of transforming growth factor alpha in the pathogenesis of Ménétrier's disease: supportive evidence form humans and transgenic mice.

Ménétrier's disease is an uncommon disorder of unknown etiology characterized by enlarged gastric folds with foveolar hyperplasia and cystic dilatation of gastric glands. Biochemical features that are seen frequently include hypoproteinemia, hypochlorhydria, and increased gastric mucus. Because transforming growth factor alpha (TGF alpha) is an epithelial cell mitogen that inhibits gastric acid secretion and increases gastric mucin content, we hypothesized that its altered expression might be involved in the pathogenesis of this disease. Therefore, we characterized TGF alpha immunoreactivity in the gastric mucosa of 4 patients with Ménétrier's disease. In contrast to the normal pattern of TGF alpha immunostaining in which TGF alpha appears most concentrated in parietal cells, there was intense staining in the majority of mucous cells in the gastric mucosa of patients with Ménétrier's disease. In one patient from whom sufficient fresh tissue was obtained to isolate RNA, expression of TGF alpha and the epidermal growth factor receptor was higher in the gastric mucosa relative to a normal control. In addition, metallothionein-TGF alpha transgenic mice, which overexpress TGF alpha in gastric mucosa, show a number of features characteristic of Ménétrier's disease. These include foveolar hyperplasia and glandular cystic dilatation, increased gastric neutral mucin staining, and reduced basal and histamine-stimulated rates of acid production. Taken together, observations derived from the human material and correlation with data from a transgenic mouse model support an important role for TGF alpha in the pathogenesis of Ménétrier's disease.

Animals↗
PubMed1992

Management of gastroduodenopathy associated with use of nonsteroidal anti-inflammatory drugs.

Adverse events associated with the use of nonsteroidal anti-inflammatory drugs (NSAIDs) are reported more frequently to the Food and Drug Administration than are those associated with any other group of drugs. The absolute risk for serious gastrointestinal events--in particular, ulcer bleeding, perforation, and death--is controversial; some investigators believe that an epidemic of NSAID-related complications is being experienced, whereas others suggest that the risks are being overemphasized. The management of patients who take NSAIDs regularly also remains controversial. Key unresolved issues include how best to identify those patients at particularly high risk for the development of ulcer complications and whether such patients should receive prophylactic therapy in an attempt to prevent such problems. In this review, we critically evaluate the currently available literature and present a management algorithm for the treatment and prevention of NSAID-associated gastroduodenopathy.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1992

Acute gastrointestinal bleeding. Experience of a specialized management team.

The initial experience of a specialized management team organized to provide expedient care for all acute major gastrointestinal bleeding in protocolized fashion at a large referral center is presented. Of the 417 patients, 56% developed bleeding while hospitalized. Upper gastrointestinal bleeding accounted for 82%. The five most common etiologies included gastric ulcers (83 patients), duodenal ulcers (67 patients), erosions (41 patients), varices (35 patients), and diverticulosis (29 patients). Nonsteroidal anti-inflammatory drugs were implicated in 53% of gastroduodenal ulcers. The incidence of nonbleeding visible vessels was 42% in gastric and 54% in duodenal ulcers. The rates of rebleeding were 24% (20 patients) in gastric ulcers and 28% (19 patients) in duodenal ulcers. Predictive factors for rebleeding included copious bright red blood, active arterial streaming, spurting, or a densely adherent clot. The rebleeding rate for esophagogastric varices was 57%. The mortality rate overall was 6% (27 patients), with rates varying from 3% (five patients) for gastroduodenal ulcers to 40% (14 patients) for esophagogastric varices. The morbidity rate for the entire patient population was 18% (77 patients), dominated by myocardial events (34 patients). The average length of hospitalization for gastroduodenal ulcers was 5 days, for diverticulosis 8 days, and for varices 10 days. The major efforts of a specialized Gastrointestinal Bleeding Team would be best directed at both reducing the morbidity associated with acute bleeding and reducing the overall cost of care.

Adolescent↗
PubMed1992

The clinical and endoscopic spectrum of the watermelon stomach.

The watermelon stomach is an uncommon but treatable cause of chronic gastrointestinal bleeding. We report our experience with the clinical and endoscopic features of 45 consecutive patients treated by endoscopic Nd:YAG laser coagulation. The prototypic patient was a woman (71%) with an average age of 73 years (range of 53-89 years) who presented with occult (89%) transfusion-dependent (62%) gastrointestinal bleeding over a median period of 2 years (range of 1 month to > 20 years). Autoimmune connective tissue disorders were present in 28 patients (62%), especially Raynaud's phenomena (31%) and sclerodactyly (20%). Atrophic gastritis occurred in 19 of 19 (100%) patients, with hypergastrinemia in 25 (76%) of 33 patients tested. Antral endoscopic appearances included raised or flat stripes of ectatic vascular tissue (89%) or diffusely scattered lesions (11%). Proximal gastric involvement was present in 12 patients (27%), typically in the presence of a diaphragmatic hernia. Endoscopic laser therapy after a median of one treatment (range of 1-4) resulted in complete resolution of visible disease in four patients (13%) and resolution of > 90% in 24 patients (80%). Hemoglobin levels normalized in 87% of patients over a median follow-up period of 2 years (range of 1 month to 6 years) with no major complications. Blood transfusions were not necessary after laser therapy in 86% of 28 initially transfusion-dependent patients. The characteristic clinical, laboratory, and endoscopic features allow for a confident diagnosis that can lead to successful endoscopic treatment.

Aged↗
PubMed1991

The mechanisms and prevention of intravascular fluid loss after occlusion of the supraceliac aorta in dogs.

Mechanisms of intravascular fluid depletion after temporary occlusion of the supraceliac aorta were investigated in a canine model. During ischemia and reperfusion, hemodynamic parameters, superior mesenteric artery flow, intestinal mucosal perfusion, and mucosal permeability were monitored. After 12 hours of reperfusion, the volumes of intravenous electrolyte fluid required to maintain hemodynamic stability and fluid lost into the gastrointestinal tract and peritoneal cavity were measured. The distribution of total body water was analyzed by use of radionuclide dilution techniques. Group A animals underwent laparotomy only, group B had the supraceliac aorta occluded for 45 minutes, group C had superoxide dismutase administered after 45 minutes of aortic occlusion, and group D animals were exposed to mild hypothermia during a similar ischemia and reperfusion period. No significant difference was found in mean superior mesenteric artery flow or mucosal perfusion during ischemia among groups B, C, and D. During reperfusion superior mesenteric artery flow returned to values similar to control in all groups. Aortic occlusion increased mucosal permeability most significantly in group B (p less than 0.01). Mean intravenous fluid requirements (ml/mg) were the following: group A, 80 +/- 5; group B, 201 +/- 9 (p less than 0.01); group C, 116 +/- 7 (p less than 0.05); group D, 245 +/- 24 (p less than 0.05). Mean gastrointestinal fluid loss was highest in the hypothermic group and smallest if superoxide dismutase was given. Mean intracellular fluid volume was increased in groups B and D compared with group A (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1990

Recent trends in the diagnosis and management of chronic intestinal ischemia.

This paper reviews the operative management over the past 27 years of 102 patients with chronic mesenteric ischemia, and summarizes recent clinical trends and ongoing research in this area. The most important trends in the diagnosis and management of chronic intestinal ischemia include: (1) increasing use of duplex ultrasound scanning in the initial evaluation of patients with possible intestinal angina; (2) rapidly evolving noninvasive clinical tests to assess mucosal perfusion (reflectance spectrophotometry, laser Doppler flow analysis, and tonometry); and (3) preferential use of antegrade mesenteric grafts or transaortic endarterectomy for mesenteric atherosclerotic occlusive disease. Surgical revascularization continues to provide excellent early relief of symptoms (93%) and a low late recurrence rate (10%). New noninvasive diagnostic tests for chronic intestinal ischemia and excellent results of surgical revascularization support a continued aggressive approach to the early recognition and treatment of patients with chronic intestinal angina. With the aging population, we anticipate that the number of patients with chronic intestinal ischemia will increase.

Angiography↗
PubMed1990

Colorectal cancer detection in the practice setting. Impact of fecal blood testing.

To assess the contribution of fecal blood testing to cancer detection in a clinical practice setting, we studied records from 160 patients with both a new tissue diagnosis of colorectal adenocarcinoma and a preceding stool blood test (HemoQuant, Mayo Medical Laboratories, Rochester, Minn) determination. In this group, 71% had suggestive colorectal symptoms (particularly stool changes, overt bleeding, and abdominal pain) or anemia at presentation, and 29% were asymptomatic. Fecal blood levels remained normal in more than 40% of both symptomatic and asymptomatic patients. In only 26 patients (16% overall) was an abnormal fecal blood level the sole heralding feature, but this subset of patients had a more favorable stage. Fecal blood levels were higher with advanced, larger, and more proximal tumors and with stools collected before purgation. We conclude that, in the practice setting, fecal blood level elevation alone is an uncommon but important manner of colorectal cancer presentation, most cancers present with symptoms, and fecal blood levels are often normal in both symptomatic and asymptomatic patients.

Abdominal Pain↗
PubMed1989

Localization of hematoporphyrin. Derivative to human colorectal cancer.

This study documents the affinity of hematoporphyrin derivative (HpD) for human colorectal cancer by analysis of surface fluorescence. Ten patients undergoing elective surgery for primary colorectal cancer received intravenous HpD (2-5 mg/kg) either 3 or 72 hours preoperatively. Fluorescent photographs were taken of freshly resected specimens and analyzed using a computerized videodensitometric technique. This technique subtracted contaminating non-HpD fluorescence and facilitated estimation of HpD tissue levels. The HpD-specific fluorescence localized to tumors in all cases, and the mean HpD concentration was six-fold greater in malignant tissue than in surrounding normal mucosa (0.6 microgram/g versus 0.1 microgram/g, P less than 0.001). The authors conclude that HpD preferentially localizes to human colorectal cancer and this is relevant to the photodetection and phototherapy of colorectal neoplasia.

Adult↗
PubMed1989

Patterns of occult bleeding in asymptomatic colorectal cancer.

The assumption that asymptomatic colorectal cancers bleed provides the rationale for widespread stool screening. The authors studied 12 patients with unoperated colorectal cancer but without colorectal symptoms and six healthy volunteers as laboratory controls. All stools were collected for 2 weeks and analyzed by the HemoQuant and Hemoccult tests. In controls, the mean HemoQuant value was 0.7 mg hemoglobin (Hb)/g stool (range, 0.1-1.8) and all stools were Hemoccult-negative. In cancer patients, the mean HemoQuant was 3.3 mg Hb/g (range, 0.3-13.2); stools were within the normal HemoQuant range (less than 2 mg Hb/g) in 38% and negative by Hemoccult in 70%. The mean cancer detection rate testing a single stool per patient was 57% for HemoQuant and 25% for Hemoccult (P less than 0.001). The detection rate rose testing multiple stools and was maximal with five stools at 83% for HemoQuant compared to 31% for Hemoccult (P less than 0.001). The authors conclude that fecal blood levels are commonly normal with asymptomatic colorectal cancer. Although higher with HemoQuant than Hemoccult, cancer detection rates by fecal blood testing appear to be lower than previously reported.

Adenocarcinoma↗
PubMed1989

Endoscopic laser therapy for watermelon stomach.

Thirteen patients (9 women, 4 men) with anemia from acute and chronic gastrointestinal bleeding were found to have antral vascular disease consistent with watermelon stomach. The median age was 73 yr, with a range of 54-88 yr. Eight of the patients were transfusion-dependent, requiring a median of 5.5 U within the 12 mo before treatment. All were treated with endoscopic neodymium:yttrium-aluminum-garnet laser coagulation. Endoscopic and hematologic improvement were evident in 12 patients available for follow-up after a median period of 6 mo. There was a median increase of 4 g/dl in hemoglobin concentration; thus, the need for transfusion was eliminated. No major complications were encountered. Laser coagulation for watermelon stomach appears to be safe and efficacious and may be a therapeutic alternative for this disorder.

Aged↗
PubMed1988

Prospective study of cutaneous phototoxicity after systemic hematoporphyrin derivative.

Hematoporphyrin derivative (HpD) is a photoactive, oncophilic substance that produces cutaneous photosensitivity as its only significant side effect. Twenty-three patients who received systemic HpD and the usual light-avoidance precautions were studied prospectively to determine the incidence and severity of cutaneous phototoxicity (CP). Seventeen of the 23 patients (74%) reported CP, including three patients (18%) who experienced blister formation. Symptoms of CP occurred for a mean duration of 6 weeks (range 5-23 weeks). Lack of compliance with restrictive photoprotective measures was felt to be a major contributing factor. Other HpD-related complications included skin hyperpigmentation, ocular discomfort, pruritus, pain at injection site, and urticaria. CP and the restrictive measures to avoid it represent major disadvantages of the clinical use of HpD.

Adult↗
PubMed1988

Measurement of degraded fecal hemoglobin-heme to estimate gastrointestinal site of occult bleeding. Appraisal of its clinical utility.

Hemoglobin-heme is variably converted to porphyrin during enterocolic transit. This intestinal converted fraction, as measured by HemoQuant, was elevated as a predictor of the occult bleeding site in 152 patients with discrete lesions. The intestinal converted fraction, expressed as the percentage of total fecal hemoglobin, was similar with upper gastrointestinal and proximal colon lesions. Within the colon, values trended downward with more distal location: means +/- standard deviations were 18 +/- 14 proximal colon, 16 +/- 15 sigmoid, and 10 +/- 10 rectum. The amount of fecal blood also affected the intestinal converted fraction; correcting for hemoglobin concentration improved separation by site. Corrected intestinal converted fraction values were significantly lower with rectal (P less than 0.0005) and sigmoid (P less than 0.02) lesions than with proximal colon lesions. Unfortunately, large within-site variation caused considerable overlap between sites. We conclude that the intestinal converted fraction is influenced by the site and amount of bleeding. However, its clinical utility is compromised by substantial individual differences in luminal hemoglobin metabolism.

Aged↗