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Biomedical subjects

J Powe

Publications and source records attributed to J Powe.

At least 37 records · Page 2Linked to original sources
PubMed1998

Neuroacanthocytosis and aprebetalipoproteinemia.

A 30-year-old woman presented with a progressive neurologic disorder characterized by seizures, buccolingual dyskinesias, orofacial tics, choreiform movements, atrophy, and areflexia. Investigations revealed normal lipid profile except for aprebetalipoproteinemia. Phase-contrast and electron microscopy showed 35 to 40% acanthocytes. MRI and 18fluorodeoxyglucose-PET studies showed caudate atrophy and hypometabolism. The phenotype of this patient is neuroacanthocytosis and its association with aprebetalipoproteinemia may represent a new subentity of the disorder.

Acanthocytes↗
PubMed1998

Fluorine-18-fluorodeoxyglucose uptake in rheumatoid arthritis-associated lung disease in a patient with thyroid cancer.

An 18F-fluorodeoxyglucose (FDG) whole-body PET scan was performed on a thyroid cancer patient with long-standing rheumatoid arthritis who presented with pulmonary nodules. A recent diagnostic radioiodine whole-body scan was negative. However, the 18F-FDG scan demonstrated intense uptake in the chest lesions as well as in several joints affected by rheumatoid arthritis. Fine-needle aspiration of a pulmonary nodule revealed inflammatory reaction and absence of malignant cells, fungus and tuberculous infection. A repeat chest CT scan after 7 mo of steroid therapy showed a marked decrease in the size and number of nodules. In thyroid cancer patients, 18F-FDG uptake in the lung may not necessarily represent pulmonary metastases. This case illustrates a benign, unrelated pathology namely, rheumatoid arthritis-associated lung disease.

Arthritis, Rheumatoid↗
PubMed1997

Radioiodine bronchogram in acute respiratory tract infection.

In this article, the authors described a 31-year-old woman with differentiated thyroid cancer is presented who had radioiodine uptake in the distribution of the tracheobronchial tree in association with symptoms of an acute respiratory tract infection. As expected, the uptake was transient and disappeared on the follow-up scan performed after 10 days of antibiotic treatment

Adult↗
PubMed1997

Cerebral manifestation of Erdheim-Chester disease: clinical and radiologic findings.

A 33-year-old woman presented with a 3-year history of progressive numbness in the hand, cerebellar ataxia, limb weakness, nystagmus, and dysarthria. T2-weighted MRI revealed abnormal foci of increased signal intensity mimicking demyelinating plaques in the periventricular white matter, and brain 18FDG-PET scan showed increased uptake in the pons. Biopsy from a tibial lesion showed aggregates of foamy histiocytes in the intertrabecular spaces replacing the bone marrow, characteristic of Erdheim-Chester disease. The patient was treated with craniospinal radiation. After 6 months, the clinical picture was stable and the MRI was unchanged.

Adult↗
PubMed1996

False-positive radioiodine uptake in the abdomen and the pelvis: radioiodine retention in the kidneys and review of the literature.

Because the kidneys are usually not visualized on radioiodine whole-body scans, the renal uptake can be mistaken for a thyroid cancer metastasis. The authors report the prevalence and characteristics of radioiodine retention in the kidneys and review the reported causes of false-positive radioiodine uptake in the abdomen and pelvic areas. Radioiodine uptake in the renal bed was noted on 9 of 400 (2.2%) I-123 diagnostic whole-body scans performed over a 7-month period in our center. The uptake was noted more clearly on posterior views, cleared on delayed images after further hydration, and was not consistently present on follow-up scans. It was unilateral and mimicked a renal or adrenal metastasis in 44% of the scans. In three cases, the uptake was associated with a dilated calyx, an extrarenal pelvis, or a voluminous pelvis. False-positive radioiodine uptake in the abdomen and pelvis has been previously reported in association with 14 different conditions. However, renal retention may represent the most common cause of false-positive radioiodine uptake in the abdomen pelvis. Delayed imaging after additional hydration is usually sufficient to clarify its origin.

Abdomen↗
PubMed1996

Isolated porta hepatis metastasis of papillary thyroid cancer.

Metastases from differentiated thyroid cancer are usually seen in the cervical or mediastinal lymph nodes, lung or bone. We report a case of papillary thyroid cancer metastasizing to lymph nodes in the porta hepatis. No other site of metastasis was apparent on neck or abdominal exploration or on iodine whole-body scans. The primary tumor was a multifocal papillary thyroid cancer arising on a background of multinodular goiter. The metastasis was observed on a diagnostic radioiodine scan after surgical resection of the primary tumor despite significant (11%) radioiodine uptake by residual thyroid tissue in the neck and was proven by histologic examination and thyroglobulin immunohistochemistry. Although rare, metastasis to porta hepatis lymph nodes should be considered in the differential diagnosis of abdominal radioiodine uptake in patients with differentiated thyroid cancer.

Adult↗
PubMed1995

Can a day 4 bone scan accurately determine the presence or absence of scaphoid fracture?

STUDY OBJECTIVE: To evaluate the accuracy of day 4 bone scans in predicting the presence or absence of fracture in patients with "clinical scaphoid fracture." DESIGN: Prospective sensitivity study of ED patients with clinical scaphoid fractures. Each patient was immobilized in a thumb spica cast and had day 4 bone scans of both wrists and hands. Blinded day 4 bone scan results were ultimately compared with the diagnosis on day 14 when patients returned for repeat clinical examination and radiographs. In cases of equivocal radiographic or clinical examination results, a day 14 bone scan was performed. SETTING: Two tertiary care teaching hospital emergency departments. PARTICIPANTS: All ED patients older than 16 years with the diagnosis of clinical scaphoid fracture were eligible. RESULTS: Ninety-nine patients were enrolled and successfully completed the study protocol from October 1990 through November 1992. One patient had bilateral injury, for a total of 100 completed studies. Day 4 bone scans were 100% sensitive and 92% specific, for a positive predictive value of 65%, a negative predictive value of 100%, and accuracy of 93% (95% confidence interval, 88%, to 98%). Many other types of fractures were identified on the day 4 scans, including those of the triquetra, distal radius, capitate, hamate, trapezoid, trapezium, and metacarpals. CONCLUSION: Day 4 bone scans are an accurate means of ruling out scaphoid fracture. However, because of a significant number of false-positive scans at day 4, they do not reliably confirm the diagnosis of scaphoid fracture. The bone scans also permitted identification of several other wrist fractures that had not been radiographically apparent.

Adolescent↗
PubMed1991

Functional results of gastric interposition following total esophagectomy.

Functional results of gastric interposition were evaluated in 35 patients at 3 to 84 months following esophagectomy. All patients were satisfied with the results of surgery, although 14 (40%) still experienced some degree of dysphagia. Transit times for radiolabeled solids across the cervical esophagus and anastomosis were not significantly different for the 14 symptomatic patients (mean 77 seconds) versus 21 asymptomatic patients (mean 55 seconds). Spontaneous emptying of the vagotomized intrathoracic stomach appeared complex, with mean percentage radionuclide clearances at 30 minutes (semisolid meal) calculated at 37% for 23 patients with early satiety (versus 42% asymptomatic) and at 38% for nine patients with reflux (versus 39% asymptomatic), all values comparable to emptying of the normal intra-abdominal stomach (35% clearance at 30 minutes). Our data suggest that the interposed stomach appears to retain its gastric identity rather than act as an inert conduit, and that although little correlation exists between postoperative symptoms and objective findings, the stomach remains a satisfactory esophageal substitute.

Adult↗
PubMed1988

Positron emission tomography in patients with glioma. A predictor of prognosis.

Positron emission tomography (PET) studies have been performed using 18-F-fluorodeoxyglucose in 29 adult subjects with primary brain tumors. Seventy-two percent of the patients were treated previously. The glucose metabolic state in the lesions was increased in 16 patients, and was normal or decreased in 13 patients. The hypermetabolic tumors tended to behave in a more malignant fashion. Patients with hypermetabolic tumors had a median survival of 7 months after PET scan, compared to 33 months for those with hypometabolic lesions. Among the high-grade glioma patients, the PET results separated them into a good prognosis group (hypometabolic, with 78% 1-year survival) and a poor prognosis group (hypermetabolic, with a 29% 1-year survival after PET). These results suggest that glucose metabolic studies may provide an independent measure of the aggressiveness of a brain tumor, and may supplement pathologic grading.

Adult↗
PubMed1987

Radioimmunodetection of human glioma xenografts by monoclonal antibody to epidermal growth factor receptor.

Murine IgG2a monoclonal antibody (MAb) 425 specifically detects epidermal growth factor receptor, which is expressed on human gliomas and tumors of other tissue origin but rarely on normal brain tissues, and not at all on bone marrow and peripheral blood cells. 131I-labeled F(ab')2 fragments of this MAb injected into nude mice grafted with U-87 MG glioma cells preferentially localized in tumor tissue compared to normal mouse tissues, as determined by differential tissue counting of radioactivity. The mean tumor-to-tissue ratios of radioactivity ranged between 8.2 (blood) and 55.8 (muscle) at 2 days after the injection of 15 muCi of 131I-425 F(ab')2/mouse. Radiolabeled fragments of an anti-hepatitis virus IgG2a MAb did not localize in tumors. The localization index derived from the ratios of specific antibody to indifferent antibody in tumor tissue relative to blood was 9.94 at 2 days following the MAb injection. The labeled MAb did not localize in a xenograft of colorectal cancer tumor, which does not express the epidermal growth factor receptor. Tumors could be located by whole-body gamma-scintigraphy without background subtraction following the injection of 100 muCi of radiolabeled MAb 425 F(ab')2 fragments. The data suggest that MAb 425 is a likely candidate for clinical diagnostic and radioimmunotherapy trials.

Animals↗
PubMed1987

The cholescintigraphic pattern of small bowel obstruction.

An elderly patient presenting with acute abdominal pain, nausea, and vomiting underwent a hepatobiliary scan. This demonstrated normal filling of the gallbladder but dilatation of the small bowel, which was found to correspond radiographically to partial small bowel obstruction.

Aged↗
PubMed1987

Tumor detection using radiolabeled monoclonal antibodies.

Radioisotope conjugated to monoclonal antibody products has been used for imaging tumors targeted by the antibody. As imaging progresses, new sets of procedural and technical questions arise. In this chapter, we discuss several current problems in imaging tumor with radiolabeled monoclonal antibody. These include (1) methods for selection of specific antibody and, once the particular antibody is selected, which fragment form is to be used; (2) imaging procedures: what are the optimum imaging parameters, such as optimum time for imaging after administration of tracer and considerations regarding background subtraction; and (3) noninvasive quantitative techniques: quantitation of localization of antibody indirectly from quantitative information in the images.

Animals↗
PubMed1986

Radioimmunodetection of human tumor xenografts by monoclonal antibody F(ab')2 fragments.

Experimental procedures are described for the radiolocalization of human tumors by murine monoclonal antibodies (MAb) in animal model systems. Visualization of tumor xenografts was clearer in nude mice as compared to experimentally immunosuppressed mice due to the higher viability of the tumors in nude mice. MAb localization in tumor tissue was greatly enhanced when F(ab')2 fragments rather than intact antibody molecules were used. Although tumors could be visualized with either 131I-, 123I- or 111In-labeled MAb fragments without using background subtraction, tumor-to-background ratios of radioactivity were highest for 131I-labeled fragments. 131I-labeled F(ab')2 fragments of eight MAb against human colorectal carcinoma, melanoma or lung carcinoma localized specifically only in those tumors that bound the MAb in vitro and not in unrelated tumors. Radiolabeled fragments of MAb with other specificities (anti-hepatitis virus MAb) did not localize in tumors. All MAb that inhibited tumor growth in nude mice effectively localized these tumors by gamma-scintigraphy. On the other hand, some MAb were effective in localizing tumors but ineffective in inhibiting their growth. The ability of the specific radiolabeled F(ab')2 fragments to localize in tumor grafts correlated significantly with MAb binding affinity and density of antigenic sites on tumor cells together, but not with either in vitro binding parameter alone. Thus, Scatchard analysis of MAb binding to tumor cells may be an effective means to screen for MAb with tumor radiolocalization potential.

Animals↗
PubMed1985

Monoclonal antibody-dependent murine macrophage-mediated cytotoxicity against human tumors is stimulated by lentinan.

The beta (1----3) glucan lentinan was tested for its capacity to increase the cytotoxic effect of murine peritoneal macrophages for human tumor cells in the presence of monoclonal antibodies (MAbs). Activity was maximum in macrophages obtained on day 5 following intraperitoneal injection of CBA mice with 2.5 mg of lentinan per kg body weight. Macrophages stimulated by lentinan were cytotoxic in conjunction with IgG1, IgG2a and IgG3 MAbs, but not with IgG2b, IgM, or IgA MAbs. The demonstration of a similar enhancing effect by lentinan on human macrophages might have implications for potentiating the tumoricidal effect of these macrophages in the presence of tumor antigen-specific MAbs.

Animals↗