Biomedical subjects

M R Christensen

Publications and source records attributed to M R Christensen.

8 recordsLinked to original sources

PubMed1999

[Fatal poisoning with Letigen].

The anorexic agent Letigen, which contains 200 mg coffeine and 20 mg ephedrine, has been extensively used during the last decade. The case report describes a 19 year-old woman who ingested 50 Letigen tablets in a suicidal attempt. She developed severe toxic manifestations from the heart, CNS, muscles, liver and kidneys leading to several cardiac arrests, and died subsequently of cerebral oedema and incarceration on the fourth day of hospitalization. Because of the potentially life-threatening intoxication following an overdose, prescription of Letigen must be carefully administered.

Adult↗

PubMed1999

Cellular proliferation in pilocytic and diffuse astrocytomas.

Using quantitative image analysis, we evaluated the MIB-1 labeling index (LI) in a large population of pilocytic (n = 131) and diffuse astrocytomas (n = 140), explored its significance as a prognostic predictor of survival, and compared it to other commonly accepted predictors, including grade and its histologic determinants, atypia, mitoses, endothelial proliferation, and necrosis. Diffuse astrocytomas were graded according to the St Anne-Mayo scheme and included 45 grade 2, 50 grade 3, and 45 grade 4 astrocytomas. In pilocytic astrocytomas, mean, median, and range of MIB-1 LIs were 1.1, 0.9, and 0-3.9%, respectively. In diffuse astrocytomas, these values were 2.3, 2, and 0-7.6% in grade 2; 6, 4.4, and 0.1-25.7% in grade 3; 9.1, 6, and 0.3-36% in grade 4. There was a significant difference in the distribution of MIB-1 LIs between pilocytic and diffuse grade 2 astrocytomas (p < 0.001), between grade 2 and grade 3 (p < 0.001), and between tumors of grade 3 and 4 (p = 0.014). Among pilocytic astrocytomas there was no association between survival and MIB-1 LI or any histologic parameter. In diffuse astrocytomas, MIB-1 LI was significantly correlated with grade as well as with mitotic activity (<0.001) and survival. While in diffuse astrocytomas of all grades, necrosis was the strongest factor associated with survival, in tumors of grades 2 and 3 the MIB-1 LI preceded other histologic parameters and, on multivariate analysis, remained the only feature predictive of survival. Grade 3 astrocytomas with a single "solitary" mitosis had a significantly lower MIB-I LI than did grade 3 tumors with >1 mitosis and, compared to the latter, had a significantly longer survival (p = 0.013), one not significantly different from patients with grade 2 astrocytomas. These findings suggest that the cutoff point between grade 2 and 3 in the St. Anne-Mayo scheme may not be optimal and may need to be revised.

Adolescent↗

PubMed1995

Effectiveness of current technology in the diagnosis and management of lower gastrointestinal hemorrhage.

Lower gastrointestinal hemorrhage is a common clinical problem for which multiple diagnostic tests and therapeutic interventions have been developed but no optimal approach has been established. We reviewed 107 consecutive patients admitted to the Massachusetts General Hospital for management of acute lower gastrointestinal hemorrhage to determine the effectiveness of diagnostic and management technologies, with particular attention to urgent colonoscopy. Colonoscopy yielded a diagnosis in 90% of patients, provided the opportunity for successful therapy in 9 of 13 patients (69%), and shortened hospital stay. Angiography performed after a scan positive for bleeding was often diagnostic, and angiography provided the means for successful therapy in 5 of 10 patients (50%). Barium enema and sigmoidoscopy had lower clinical yields. Although roles exist for other technologies, colonoscopy is the most convenient and effective first test in the evaluation of patients with significant lower gastrointestinal hemorrhage. Diagnostic yield, therapeutic opportunity, and cost effectiveness are maximized in early studies.

Acute Disease↗

PubMed1989

Angiodysplasia. Natural history and efficacy of therapeutic interventions.

Angiodysplasia, a disease for which the optimal treatment is uncertain, is a frequent cause of lower intestinal bleeding among older patients. To study the natural history of angiodysplasia and compare the efficacy of medical therapy, endoscopic electrocoagulation, and surgery, the course of 101 patients evaluated from 1974 through 1983 at the Massachusetts General Hospital was reviewed. Angiodysplasia caused bleeding that ranged from occult blood in stools to massive hemorrhage and was also observed incidentally in nonbleeding patients. Patients were followed for up to 10 years (mean of 22 months). Rebleeding was defined as evidence of hemorrhage requiring hospital admission, transfusion, or surgery. Thirty-one patients were treated surgically, 19 patients were treated endoscopically, and 36 patients were treated medically. Using life table analysis we observed similar rebleeding rates among medically and endoscopically treated groups. The surgically treated group had a frequency of rebleeding less than half that of the other groups (P = 0.15). A multivariate regression analysis failed to identify any factors other than coagulopathy to explain the different incidence of rebleeding in the patients treated by endoscopic electrocoagulation and surgery.

Diverticulum↗

PubMed1989

The clinical utility of the Ca19-9 radioimmunoassay for the diagnosis of pancreatic cancer presenting as pain or weight loss. A cost-effectiveness analysis.

CA 19-9 is a promising radioimmunoassay for the detection of pancreatic cancer, but its clinical role and cost-effectiveness are not yet known. To investigate these factors, we used clinical decision analysis to study diagnostic strategies for patients with suspected pancreatic cancer presenting as pain or weight loss. Comprehensive diagnostic strategies were developed to reflect current and future patterns of practice utilizing CA19-9 radioimmunoassay (RIA) to yield biopsy-proved cancer or confidently exclude its presence. The performance of the strategies beginning with CA19-9 RIA and ultrasonography were equivalent in positive and negative predictive values over a range of prevalence of pancreatic cancer from 0.02 to 0.15. At higher prevalence, the negative predictive value of the ultrasonography strategy became significantly better. The CA19-9 RIA strategy used fewer noninvasive tests, endoscopic retrograde cholangiopancreatographic procedures, and invasive radiologic studies than did the ultrasonography strategy at each prevalence. The health care costs ranged between $848 and $1413 per patient for the CA19-9 RIA strategy and $1186 and $1848 per patient for the ultrasonography strategy. We conclude that the CA19-9 RIA is a useful, cost-effective initial test for the examination of patients with suspected pancreatic cancer.

Antigens, Tumor-Associated, Carbohydrate↗

PubMed1987

Chronic cholecystitis. An analysis of diagnostic strategies.

To define the optimal diagnostic approach for suspected chronic cholecystitis comprehensive management strategies were developed. Using a computer model, the frequency of appropriate surgery, inappropriate surgery, complications, death, and medical costs were compared in populations of patients with various disease prevalences. The optimal strategy began with ultrasonography, followed by an oral cholecystogram when the ultrasonogram was inconclusive. Oral cholecystogram also was employed when additional diagnostic studies failed to provide another explanation for the patient's symptoms. Compared with strategies using only ultrasonography or oral cholecystography, the combination strategy lowered the frequency of inappropriate surgery from 7.1 to 4.4% and direct medical costs from $1,877 to $1,766 per patient in a population with a 20% prevalence of chronic cholecystitis. The differences persisted at higher prevalences of cholecystitis and when sensitivities and specificities of the tests were varied over ranges reported in the literature. Diagnostic accuracy and direct medical costs could be improved by a more frequent interpretation of subtle abnormal ultrasonographic findings as inconclusive and by a more liberal use of oral cholecystography. This analysis demonstrates that a strategy combining ultrasonography and oral cholecystography is superior to the use of either test alone and is cost-efficient.

Cholecystitis↗

PubMedDate not supplied

Endoscopic palliation of obstructive esophagogastric malignancy.

To investigate the efficacy of alternative endoscopic palliative therapies for obstructive esophagogastric malignancy, the experience of 53 patients treated between 1979 and 1986 was analyzed. Forty-seven patients had placement of intraesophageal prostheses. Ten patients had prostheses placed after neodymium:YAG laser therapy. In four of these patients, prosthesis placement was planned as part of the initial therapy. Twelve patients initially received laser therapy. In six, recurrent tumor was treated with intraesophageal prostheses 3 to 24 weeks after laser treatment. Comparing neodymium:YAG laser therapy to placement of the prosthesis, both techniques provided similar improvement in dysphagia. Patients receiving prostheses required less additional treatment for dysphagia. Life table analysis comparing survival rates from diagnosis to death showed no difference. The palliation provided by prostheses and neodymium:YAG laser appears to be quite similar; however, the prosthesis seems to be more lasting and require fewer resources.

Adenocarcinoma↗

PubMedDate not supplied

Pesticide residues in selected food commodities: results from the Danish National Pesticide Monitoring Program 1995-1996.

The paper presents results of analyses of 4182 samples collected from January 1995 to December 1996 for the Danish National Pesticide Monitoring Program. The program basis is a random sample control supplemented with a target control. The objectives of the control are to monitor consumer exposure to health hazards and to enforce national and European Community regulations. The Danish Veterinary and Food Administration is responsible for establishing methods, data manipulation, and evaluation, but actual analyses are performed at 4 regional laboratories. In addition to a description of the Danish National Pesticide Monitoring Program on food, the effects of lowering the reporting limits are discussed. Pesticides included are those in current use as well as chlorinated pesticides like lindane, DDT, and HCB, occurring in food now primarily as a result of environmental contamination. Commodities analyzed are fruits, vegetables, cereals, bran, fish, and animal products such as meat, butter, cheese, fat, and eggs. In fruits and vegetables, residues were detected in 10% of 2515 samples, with higher incidences of detection for foreign commodities. Violation rate was 0.6%. In food of animal origin, low levels of organochlorine pesticides were detected in most fish samples and in more than half of the animal product samples. However, no results exceeding maximum residue limits were found. No residues of organophosphorus pesticides were detected in the 231 meat samples analyzed.

Animals↗