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Biomedical subjects

A M Scott

Publications and source records attributed to A M Scott.

At least 91 records · Page 5Linked to original sources
PubMed1994

Imaging of brain tumor proliferative activity with iodine-131-iododeoxyuridine.

METHODS: Iodine-131-iododeoxyuridine (IUdR) uptake and retention was imaged with SPECT at 2 and 24 hr after administering a 10-mCi dose to six patients with primary brain tumors. The SPECT images were directly compared to gadolinium contrast-enhanced MR images as well as to [18F]fluorodeoxyglucose (FDG) PET scans and 201Tl SPECT scans. RESULTS: Localized uptake and retention of IUdR-derived radioactivity was observed in five of six patients. The plasma half-life of [131I]IUdR was short (1.6 min) in comparison to the half-life of total plasma radioactivity (6.4 hr). The pattern of [131I]IUdR-derived radioactivity was markedly different in the 2-hr compared to 24-hr images. Radioactivity was localized along the periphery of the tumor and extended beyond the margin of tumor identified by contrast enhancement on MRI. The estimated levels of tumor radioactivity at 24 hr, based on semiquantitative phantom studies, ranged between < 0.1 and 0.2 microCi/cc (< 0.001% and 0.002% dose/cc); brain levels were not measurable. CONCLUSIONS: Iodine-131-IUdR SPECT imaging of brain tumor proliferation has low (marginal) sensitivity due to low count rates and can detect only the most active regions of tumor growth. Imaging at 24 hr represents a washout strategy to reduce 131I-labeled metabolites contributing to background activity in the tumors, and is more likely to show the pattern of [131I]IUdR-DNA incorporation and thereby increase image specificity. Iodine-123-IUdR SPECT imaging at 12 hr and the use of [124I]IUdR and PET will improve count acquisition and image quality.

Adult↗
PubMed1994

Linear keloids resulting from abuse of anabolic androgenic steroid drugs.

Anabolic androgenic steroid use by professional and amateur athletes is widespread. Dermatologic side effects are among the most frequent complications. Linear keloids are an unusual manifestation. Athletes rarely volunteer, or even admit, that they are taking such steroids. These drugs are taken in cycles and gas chromatography--mass spectrometry is the preferable urinary test for detecting their presence.

Anabolic Agents↗
PubMed1993

Characterization of canine microsatellites.

Canine DNA was cloned in M13 and screened for the presence of (dC-dA)n.(dG-dT)n repeats. Oligonucleotide primers were synthesised to the microsatellite flanking sequences and used in the polymerase chain reaction to amplify those loci from genomic DNA. The polymorphism of each microsatellite was estimated in a set of unrelated dogs.

Animals↗
PubMed1993

Intragastric distribution and gastric emptying of solids and liquids in functional dyspepsia. Lack of influence of symptom subgroups and H. pylori-associated gastritis.

The relative contributions of altered gastric motor function and Helicobacter pylori-associated active chronic gastritis to the pathogenesis of functional dyspepsia are controversial. We therefore evaluated scintigraphically the intragastric distribution and gastric emptying of a mixed solid-liquid meal in 75 patients with functional dyspepsia; patients were subdivided on the basis of both specific symptom clusters and the presence or absence of H. pylori gastritis. Twenty-one (28%) patients displayed abnormal solid and/or liquid gastric emptying, with prolonged solid lag time the most prominent alteration detected. The number of patients with abnormal scintigraphic patterns increased to 36 (48%) when intragastric distribution parameters (fundal half-emptying time and antral maximal fraction) were examined. Although patients with reflux-like dyspepsia (N = 36) demonstrated significantly slower rates of liquid emptying at 45 and 70 min and a higher prevalence of abnormal liquid intragastric distribution when compared to patients with motility-like dyspepsia (N = 39) or to controls (N = 34), the absolute differences were small and unlikely to be of clinical significance. Patients without H. pylori gastritis (N = 50) demonstrated a significantly more prolonged solid lag time when compared to those with H. pylori gastritis (N = 25), but the difference was small and there were no other differences between these two subgroups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Effects of cigarette smoking on solid and liquid intragastric distribution and gastric emptying.

BACKGROUND: The acute effects of cigarette smoking on gastric emptying are controversial, whereas its effects on the intragastric distribution of solids and liquids are not established. METHODS: Dual isotope gastric scintigraphy was performed in 15 habitual smokers (studied twice, either sham smoking or actively smoking) and in 15 age- and sex-matched nonsmokers. RESULTS: Acute smoking was associated with an increased prevalence of episodes of retrograde intragastric movement of solids (3 of 15 sham subjects vs. 12 of 15 actively smoking subjects; P < 0.01) and of liquids (0 of 15 vs. 7 of 15; P < 0.01) from distal to proximal stomach. Fundal half-emptying time (T1/2) for liquids was also prolonged by smoking (43 +/- 19 minutes sham vs. 125 +/- 216 minutes active; P < 0.05). Acute smoking delayed solid lag time (13 +/- 6 minutes sham vs. 32 +/- 18 active; P < 0.05) and liquid T1/2 (46 +/- 21 vs. 90 +/- 50 minutes; P < 0.05). In the nonsmokers, such episodes of proximal intragastric redistribution did not occur, and intragastric and overall emptying parameters did not differ significantly from those of habitual sham smokers. CONCLUSIONS: Acute cigarette smoking produces excessive antrofundal redistribution of both solid and liquid contents and delays solid and liquid gastric emptying.

Adult↗
PubMed1993

Hiatal hernia on whole-body radioiodine survey mimicking metastatic thyroid cancer.

Total body I-131 scanning done on a 67-year-old woman with thyroid cancer revealed abnormal tracer uptake within the mid-thorax, thought to represent metastasis in the mediastinum or thoracic spine. Single-photon emission computed tomography images of the thorax showed contiguity between the thoracic uptake and the normal, physiologic uptake of radioiodine in the stomach, suggesting physiologic accumulation within a hiatal hernia. To confirm the alimentary tract location of the radioiodine, a study using orally administered Tc-99m SC in water was performed. The images were similar to the iodine images and revealed a pattern consistent with hiatal hernia. A hiatal hernia was also observed as an incidental finding on chest radiographs and an MRI. This case illustrates the potential for an abnormal anatomic configuration to mimic metastatic thyroid cancer and shows how SPECT and oral Tc-99m SC images may be useful in making this distinction.

Aged↗
PubMed1993

Recent achievements in the development of radiolabeled monoclonal antibodies for diagnosis, therapy and biologic characterization of human tumors.

Human tumors express antigenic sites that can serve as targets for radiolabeled monoclonal antibodies for diagnosis, therapy and biologic characterization of human tumors in vivo. Over the last decade, nearly 200 clinical trials have been performed which demonstrate that tumors can be detected with excellent sensitivity and specificity. Tumors which are otherwise occult, particularly for colorectal (anti-CEA and anti-TAG-72 antibodies) and ovarian cancer (anti-TAG-72 and anti-HMFG), are detected in a significant fraction of problem patients. Therapy using radiolabeled antibodies has been effective in lymphomas, leukemias and neuroblastomas, and is beginning to show promise in other solid tumors. Biologic characterization of tumors is likely to become more and more important in the future as monoclonal antibodies against oncogene products, such as her-2-neu, are developed. Development of new antibody forms through genetic engineering techniques, and the continual evolution toward higher resolution imaging instruments, such as PET and SPECT, will lead to further clinical improvements in cancer detection.

Antibodies, Monoclonal↗
PubMed1993

Tumor imaging and therapy.

Oncology applications in nuclear medicine include both the staging of tumors, e.g., bone scanning, and monitoring response to therapy with tumor-specific radionuclides such as 67Ga-citrate and 201Tl-chloride. An increasing role for positron emission tomography and monoclonal antibody studies in oncology is emerging, and therapeutic applications in thyroid cancer and in the treatment of metastatic bone pain are achieving impressive results. This area is likely to become the fastest growing component of nuclear medicine practice over the next decade.

Humans↗
PubMed1993

Lesion-by-lesion comparison of computerized tomography and indium-111-labeled monoclonal antibody C110 radioimmunoscintigraphy in colorectal carcinoma: a multicenter trial.

C110 is an anti-carcinoembryonic antigen murine IgG1 monoclonal antibody. Indium-111-labeled C110 radioimmunoscintigraphy (RIS) in colorectal cancer was studied in 51 presurgical patients at four institutions. Planar and SPECT images were obtained at least twice between 48 and 96 hr after injection of 5 mCi/5 mg of 111In-C110. Fifty-one patients had 87 biopsy-proven lesions at surgery (57 hepatic, 30 extra-hepatic). Thirty-three patients (64.7%) had positive radionuclide scans, while 32 (62.8%) had positive CT scans (p = NS). While CT was better at overall lesion detection (62.1% versus 56%, p < 0.05), radionuclide scans were better than CT for extra-hepatic disease (60% versus 46.7%, p < 0.01). Hepatic metastases (52.6%) were visualized by Mab scans to selectively concentrate radioactivity. Uptake in draining lymph nodes was a significant limitation, making evaluation of these sites difficult. Indium-111-C110 shows selective uptake in metastatic colorectal cancer, including more than half of all hepatic lesions evaluated.

Adult↗
PubMed1992

Cigarette smoking and nicotine delay postprandial mouth-cecum transit time.

The acute effects of both cigarette smoking and nicotine on postprandial mouth-cecum transit were studied in 20 habitual smokers, 10 males and 10 females. Mouth-cecum transit time was measured by the breath hydrogen technique, following ingestion of a standard mixed liquid meal. Each subject was studied on four separate occasions, either (1) sham or actively smoking two standard cigarettes, commencing 20 min after the meal, or (2) chewing two placebo or nicotine tablets over a 60-min period, commencing immediately after the meal. The time of administration of these stimuli was designed to minimize the effects on mouth-cecum transit time of alterations in gastric emptying. Mouth-cecum transit time was prolonged in response to both smoking [median and interquartile range: 120 (95, 150) min vs 100 (75, 140) min, P = 0.01] and nicotine [120 (80, 170) min vs 100 (70, 140) min, P = 0.002]. No difference was observed between sexes with respect to nicotine; the effect of smoking on mouth-cecum transit time, however, was less pronounced in females compared to males [difference active-placebo: 10 (10, 20) min vs 35 (20, 60) min, P = 0.01]. We conclude that acute cigarette smoking delays mouth-cecum transit time, an effect most likely due to nicotine.

Adult↗
PubMed1992

Suppression of anger and gastric emptying in patients with functional dyspepsia.

Psychologic distress and gastric motor dysfunction have both been implicated in the pathogenesis of functional (non-ulcer) dyspepsia (FD). This study assesses the association between psychologic factors and gastric emptying in 28 FD patients. Subjects completed an extensive range of psychologic questionnaires and underwent dual-isotope scintigraphic assessment of solid and liquid gastric emptying. Attempts to resist, control, suppress, and hold in anger, to adopt a fighting spirit whilst dealing with chronic stressors, and manifest unhappiness were predictors of prolonged gastric emptying. These findings suggest that psychologic factors may be important in the aetiology of gastric stasis and subsequent upper gastrointestinal symptoms in patients with functional dyspepsia.

Adaptation, Psychological↗
PubMed1992

Effects of anabolic-androgenic steroids on the pilosebaceous unit.

Examination of skin biopsy specimens from persons using anabolic-androgenic steroids demonstrates dramatic hypertrophy of the sebaceous glands. High dosages of testosterone and anabolic-androgenic steroids, often self-administered by athletes, increase skin surface lipids, the cutaneous population of Propionibacteria acnes and the cholesterol and free fatty acids of the skin surface lipids. Acne, oily hair and skin, sebaceous cysts, hirsutism, androgenic alopecia, striae atrophicae, seborrheic dermatitis, and secondary infections including furunculosis may occur in persons using these drugs.

Acne Vulgaris↗
PubMed1992

Comparison of technetium-99m-MIBI and thallium-201-chloride uptake in primary thyroid lymphoma.

A case of primary thyroid lymphoma demonstrating uptake of 99mTc-hexakis-2-methoxy isobutyl isonitrile (MIBI) is presented. The 99mTc-MIBI image more clearly delineated the extent of tumor as demonstrated on CT compared to 201Tl-chloride and [99mTc]pertechnetate images. Following two courses of chemotherapy, repeat radionuclide studies and CT scan showed complete resolution of the thyroid tumor. Technetium-99m-MIBI may be useful in the assessment of disease activity and monitoring response to treatment in patients with lymphoma.

Female↗
PubMed1990

Pulmonary toxicity of thioureas in the rat.

Administration of alpha-naphthylthiourea (ANTU) to rats causes damage to pulmonary endothelial cells and possibly mesothelial lining cells that together may account for the massive pleural effusion characteristic of thiourea toxicity. Using 35S-thiourea as a model compound, the extent of binding of 35S to lung proteins correlated well with the extent of edema, suggesting that the extent of binding of thiourea metabolites is a measure of lung toxicity. ANTU and phenylthiourea (PTU) compete for 35S binding to lung slices, suggesting that these toxins may act in a similar way. Binding of 35S in lung slices from resistant rats is much less than in controls, and resistance cannot be explained by differences in either whole body metabolism or redistribution of thiourea in vivo. Lung glutathione levels (in vitro and in vivo) in normal and resistant rats following thiourea administration were essentially the same. However, at doses of thiourea that cause pleural effusion, there was an increase in total lung glutathione.

Animals↗
PubMed1990

Epilation.

An ancient manual technique of epilation still in common usage, and modern electrical epilating devices, are compared. Folliculitis may occasionally be produced by either type of procedure.

Female↗
PubMed1988

Novel alpha haemoglobin haplotypes in horses.

Four minor haplotypes that produce abnormal haemoglobin phenotypes in horses have been characterized. Two of them, AIIb and V, are copy number variants with, respectively, one and three alpha genes instead of the normal complement of two. The AIIa and C haplotypes, on the other hand, each have two alpha genes but, as a result of probable gene conversions, they now encode identical, though haplotype specific, globins. Two out of 60 unrelated and phenotypically normal horses studied had an unusual triplicated rearrangement in the embryonic zeta-gene locus. Each of these variants appears to have been produced by aberrant recombination events.

Animals↗