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Biomedical subjects

R T Morrison

Publications and source records attributed to R T Morrison.

At least 19 recordsLinked to original sources
PubMed1997

Edema and principles of diuretic use.

Diuretics have changed the approach to many disease and have turned once fatal conditions into tolerable ones. Treatment of salt and water overload and edema can be quite satisfying for the clinician as long as the patient is closely watched for side effects. Thiazide diuretics have their greatest use in hypertension, loop diuretics in edema and congestive heart failure, CA inhibitors in glaucoma and altitude sickness, potassium-sparing diuretics in hypokalemia induced by other diuretics and ascites, and osmotic diuretics in acute renal failure and dialysis. They are among the most widely prescribed medications in the world today and rightly have a prominent place in the armamentarium against disease.

Diuretics↗
PubMed1996

A comparison of outcome criteria in the diagnosis of renovascular hypertension.

The outcome criteria used for the diagnosis of renovascular hypertension (RVHT) following renal revascularization have not been validated. Differing criteria of indeterminate accuracy have yielded conflicting conclusions concerning the prevalence and efficacy of treatment of RVHT. We compared the accuracy of conventional outcome criteria used in the diagnosis of RVHT to that of novel, ordered outcome analysis to determine whether such an analysis might provide a more consistent means of diagnosing RVHT. Twenty-seven patients underwent intervention for treatment of presumed RVHT (group I), and 40 patients with presumed essential hypertension were treated with antihypertensive medication alone (group II). A standard dichotomized (improved or unimproved) outcome scheme and a five-level, ordered outcome scheme (ranging from definitely unimproved to definitely improved) were used to generate nominal outcomes of therapy for each patient. The resultant outcome groups were examined to determine the effect of such partitioning on blood pressure and medication requirements. To determine their diagnostic accuracy, the conventional and ordered outcome schemes were compared with a consensus outcome scheme derived from the use of numerous criteria. Significant correlations were observed between the ordered outcome score and posttreatment reductions in systolic blood pressure (r = 0.53, p = 0.007), diastolic blood pressure (r = 0.74, p = 0.0001), and medication score (r = 0.71, p = 0.0001). Overall diagnostic accuracy was estimated to be 91% for ordered criteria and 85% for dichotomized criteria. Correlation of the ordered and conventional schemes' assignments with the consensus scheme's assignments was 0.79 (p = 0.0001) and 0.63 (p = 0.0001), respectively. A simple, ordered outcome scheme compares favorably with the standard dichotomized scheme in assigning a diagnosis of RVHT to patients following renal revascularization or nephrectomy. The ordered scheme offers the advantages of simplicity and accuracy over current schemes.

Aged↗
PubMed1995

The determination of low levels of radiocaesium and radioruthenium in foodstuffs.

The Ministry of Agriculture, Fisheries and Food (MAFF) has the responsibility for safeguarding the food supply from authorised and accidental releases of radioactivity to the environment. MAFF funds a radiological research programme to assist in the achievement of its objectives and has recognised that there is a continuing requirement to develop cost effective and sensitive analytical methods for the detection of very low levels of radioactivity in foodstuffs. High resolution gamma spectrometry is often the most appropriate analytical method for the determination of 103Ru, 106Ru, 134Cs and 137Cs but the detection limits for these radionuclides in bulk foodstuffs do not permit the acquisition of accurate data at very low levels. Beta counting techniques offer inherently higher sensitivities but the development of radiochemical separation techniques is essential to provide appropriate counting sources. A radiochemical separation method has been developed for the determination of radiocaesium and radioruthenium in 0.5 kg fresh wt samples of a variety of foodstuffs. The method was shown to be robust and specific and mean method recoveries of 75% were obtained for both radiocaesium and radioruthenium. MDA's for the 1000 min counts on a gas-flow proportional counter were determined to be 0.015 Bq/kg fresh wt for both 137Cs and 106Ru.

Cesium Radioisotopes↗
PubMed1995

Determination of strontium-90 in milk samples using a controlled precipitation clean-up step prior to ion-chromatography.

Strontium-90 may be determined by beta-counting its yttrium-90 daughter following separation by ion-chromatography, using a three column system comprising a chelating concentrator column, a cation-exchange column and an anion-exchange separator column. The column system has previously been applied to the determination of strontium-90 in water and urine samples. The applicability of the system to the analysis of milk is hampered by the large concentrations of calcium present, which significantly reduces the extraction of yttrium-90 by the concentrator column. A maximum of approximately 200 mg of calcium can be present for the successful extraction of yttrium-90, which greatly limits the quantity of milk that can be analysed. The quantity of milk analysed can be increased by the inclusion of a controlled precipitation step prior to the ion-chromatographic separation. The precipitation is carried out on acid digested milk samples by the addition of ammonia solution until the addition of one drop causes a reduction in pH resulting in the precipitation of calcium hydrogenphosphate. Under these conditions, approximately 20% of the calcium present in the original milk sample is precipitated, yttrium-90 is precipitated whereas strontium-90 is not precipitated. Dissolution of the precipitate, followed by separation of yttrium-90 using the ion-chromatography system facilitates the analysis of a litre of milk with recoveries of greater than 80%.

Animals↗
PubMed1995

Multifocal uptake of Tc-99m mebrofenin in dilated liver ductules in a patient with cystic fibrosis.

A patient with cystic fibrosis and a previous cholecystectomy, underwent Tc-99m mebrofenin scintigraphy to rule out hepatobiliary disease. The scan revealed multiple focal collections of radiopharmaceutical within the liver parenchyma. This unusual pattern of multiple focal parenchymal activity may be specific for patients with cystic fibrosis. This is the first time this unusual pattern has been confirmed at autopsy.

Adult↗
PubMed1995

Delayed massive soft tissue uptake of Tc-99m MDP after radiation therapy for cancer of the breast.

A patient with a history of breast cancer and known lung metastases was referred for a bone scan to investigate the cause of severe neck and right shoulder pain. The bone scan showed massive uptake of the radiopharmaceutical in the soft tissue surrounding the right shoulder. A review of the patient's history indicated that the patient had undergone radiation therapy to the right upper thorax and breast area 14 months previously and an acute radiation dermatitis of the proximal right arm and should had developed. This had long since resolved. Physical examination and plain radiographs of the right shoulder and humerus failed to demonstrate any abnormality.

Aged↗
PubMed1994

Determination of strontium-90 in water and urine samples using ion chromatography.

A semi-automated method was developed for the determination of 90Sr in water and urine samples using ion chromatography. Yttrium-90 in secular equilibrium with 90Sr was initially extracted from the sample solution buffered to pH 5 using a high-capacity iminodiacetate chelating resin. At this pH, transition metals, lanthanides and actinides were extracted by the resin. The extracted metals were then transferred on to a separator column where they were separated and eluted as weak acid anionic complexes. The transition metals were eluted first by using a pyridine-2,6-dicarboxylate eluent, then the lanthanides, actinides and 90Y were eluted from the column by using an oxalate-diglycolate eluent. The fraction containing 90Y was then collected and beta-counted. For water samples, a minimum of sample preparation was required prior to chromatography, whereas an oxalate coprecipitation was included as a preconcentration step for urine samples. The derived recoveries for 90Sr for surface water, rain water and urine samples were 91.7 +/- 1.8, 91.9 +/- 1.6 and 90.0 +/- 2.7%, respectively, and the minimum detectable activity using gas flow proportional counting was 8 mBq.

Chromatography↗
PubMed1992

Fracture of the laryngeal cartilage. An incidental finding on bone scintigraphy.

A patient complaining of headaches and bone pain at multiple sites had Tc-99m MDP scintigraphy performed for possible bone trauma after a motor vehicle accident. Bone imaging revealed a small focal increase in tracer uptake in the area of the laryngeal cartilage. There was some reluctance to place a label on this abnormality because the findings were so unusual. The initial diagnosis was a probable fracture of the laryngeal cartilage. Computed tomography of the neck also demonstrated a fracture but correctly localized it to the thyroid cartilage.

Adult↗
PubMed1985

Technetium 99m-methylene diphosphonate bone scans in children with reflex neurovascular dystrophy.

Eleven children with reflex neurovascular dystrophy were investigated by technetium-labeled methylene diphosphonate bone scanning. Eight of 12 scans demonstrated abnormal findings, four showing diffusely decreased uptake and four diffusely increased uptake of the radionuclide in the affected site. Three scans showed normal findings initially, as did one previously abnormal scan when repeated in the asymptomatic patient 6 months later. Diffusely abnormal findings can be helpful in the diagnosis of childhood reflex neurovascular dystrophy, but a normal scan does not exclude the diagnosis.

Adolescent↗
PubMed1985

Comparison of technetium-99m pyrophosphate and technetium-99m methylene diphosphonate with variable amounts of stannous chloride in the detection of acute myocardial infarction.

The authors prospectively compared the ability of Tc-99m pyrophosphate (PYP) and Tc-99m methylene diphosphonate (MDP) to detect acute myocardial infarctions. The agents used were PYP (12 mg) with 3.4 mg of stannous chloride, MDP (10 mg) with 1.0 mg of stannous chloride, and MDP (10 mg) with 3.4 mg of stannous chloride. Imaging was performed on three consecutive days on 34 patients with proven myocardial infarctions, using the same agent on the first and third days of the study and an alternate agent on the second day. Agents were assigned randomly to each of six groups of patients. First images were obtained an average of 3.7 days (range, one to six days) following myocardial infarction. Seventeen of 23 patients (75%) had images positive for acute myocardial infarction with Tc-99m PYP, whereas only two of 21 patients (9.5%) had positive studies with Tc-99m MDP with 3.4 mg of stannous chloride and one of 24 patients (4.2%) had positive studies with Tc-99m MDP and 1.0 mg of stannous chloride. All three myocardial infarctions detected by Tc-99m MDP were extensive and transmural. When MDP and PYP were both positive in the same patient, the apparent size of the myocardial infarction was much smaller with the MDP. It is concluded that MDP can detect only large myocardial infarctions, has poor localization in the infarcted tissue, and varying the stannous chloride content of the preparation does not improve the ability of MDP to detect acute myocardial infarctions.

Adult↗
PubMed1985

Technetium-99m-labelled red blood cell scanning to diagnose occult gastrointestinal bleeding.

The authors, from their experience in 60 patients, demonstrate that technetium-99m-labelled red blood cell scintigraphy is a sensitive (91%) and specific (76%) diagnostic procedure with a high predictive value, when both positive (81%) and negative (92%). It is preferable to and more cost-effective than selective angiography as a first-line diagnostic test for occult gastrointestinal bleeding.

Cecal Diseases↗
PubMed1984

Gamma scintigraphy using Tc-99m labeled antibody to human chorionic gonadotropin.

A case report is presented describing a 27-year-old woman with invasive trophoblastic hydatidiform mole metastatic to the lung. Gamma scintiscanning, using a polyclonal and monoclonal antibody specific to human chorionic gonadotropin, hCG, and labeled with Tc-99m, is described. The area of the primary lesion in the uterus was demonstrated with both antibodies tested without computer subtraction techniques; metastatic deposits in the lung were detected only with the aid of blood pool subtraction techniques.

Adult↗
PubMed1982

Leaking Glenn anastomosis demonstrated by first pass radionuclide angiography.

First pass radionuclide angiography was used to demonstrate a leaking Glenn anastomosis at the superior vena cava--right atrial junction as well as tricuspid atresia and a ligated persistent left superior vena cava. First pass radionuclide angiography may demonstrate anatomic configurations not obvious at cardiac catheterization and can be useful for adults with complicated congenital heart disease, particularly when biplane or multiple view angiography is not possible. Lung perfusion imaging can lead to an incorrect diagnosis of pulmonary embolism if the presence of a Glenn anastomosis in not known.

Adult↗
PubMed1977

Ultrasound diagnosis of splenic cysts.

Ultrasound is an effective modality for the study of splenic cysts because it is able to distinguish between cystic and solid lesions. Three cases of splenic cyst are presented in which definitive diagnosis was made with ultrasound B-scan.

Adolescent↗