Search PubMed⌕ Search

Biomedical subjects

A Alavi

Publications and source records attributed to A Alavi.

At least 253 records · Page 14Linked to original sources
PubMed1990

Detection of thrombophlebitis with 111In-labeled anti-fibrin antibody: preliminary results.

Deep venous thrombosis remains a major medical problem, affecting a large segment of the population and resulting in significant mortality and morbidity. Current techniques available for detecting deep venous thrombosis present limitations that may mitigate their potential benefit to the patient. Invasive techniques, such as ascending contrast venography, carry risks to the patient with regard to complications such as an allergic reaction to an iodine dye, adverse effects to renal functions, and clot formation in a normal vein. Noninvasive techniques, such as Doppler ultrasound and impedance plethysmography, evaluate only a limited segment of the venous bed. The need remains for a diagnostic technique that is safe, accurate, and widely accessible. A readily available noninvasive scintigraphic technique utilizing radiolabeled monoclonal anti-fibrin antibody may overcome some of these shortcomings. This imaging examination is quite effective in detecting clots in the lower extremities. Compared to contrast venography, 111In-labeled anti-fibrin antibody imaging appears to be as sensitive in identifying acute venous thrombosis. In addition, the preliminary data indicate that anticoagulation with heparin may interfere with adequate visualization of the clots with this technique.

Adult↗
PubMed1990

Relation of hyperglycemia early in ischemic brain infarction to cerebral anatomy, metabolism, and clinical outcome.

We studied the relation of serum glucose level measured in the first 12 hours of symptoms to the clinical findings, results of computed tomography (CT), and patterns of cerebral metabolism in 39 patients who had acute ischemic cerebral infarction. Structural damage was assessed by CT. Metabolic disruption was assessed using 18F-fluorodeoxyglucose and positron emission tomography (PET). Median initial serum glucose concentration was 155 mg/dl (6.7 mM). Clinical recovery was significantly poorer in patients with initial serum glucose levels higher than the median (p less than 0.05, chi square). PET tended to show normal results or minor abnormalities in patients with initial glucose levels less than the median, as opposed to lobar or multilobe abnormalities in patients with levels that were higher than the median (p less than 0.05, Kendall's Tau b). The severity of hypometabolism in the ischemic region, expressed as the percent asymmetry of local cerebral glucose metabolism between homologous brain regions, was greater in patients with initial glycemia concentrations higher than the median (p less than 0.001, t test). Relationships of serum glucose level with metabolic derangement and structural damage, but not outcome, held true in patients without a history of diabetes mellitus.

Aged↗
PubMed1990

Middle cerebral artery strokes causing homonymous hemianopia: positron emission tomography.

Eight patients were evaluated with 18F-fluorodeoxyglucose positron emission tomography between 3 and 30 days after isolated stroke involving the middle cerebral artery territory that caused homonymous hemianopia. Diffuse hypometabolism was present throughout the damaged cerebral hemisphere, even in cortical areas not obviously ischemic by clinical examination or neuro-imaging. Glucose metabolism in primary and association visual cortex of the damaged hemisphere was decreased by more than 47% (p less than 0.01). Metabolism in the undamaged hemisphere was less profoundly affected, but significant decrements were found in calcarine (40%; p less than 0.01) and lateral occipital cortex (35%; p less than 0.05).

Brain Ischemia↗
PubMed1990

The effect of focal cerebral atrophy in positron emission tomographic studies of aging and dementia.

We used x-ray computed tomographic (XCT) scans to measure the degree of cerebral atrophy in brain regions defined by a region of interest (ROI) anatomy atlas. The same atlas was employed for quantitation of local cerebral glucose metabolic rates (LCMRglc) by PET. PET data were obtained from 9 young controls, 7 healthy elderly controls, and 10 patients with dementia. Cerebrospinal fluid (CSF) in atrophic brain regions was assumed to be metabolically inert, and LCMRglc measurements were corrected for the degree of atrophy. Significantly greater atrophy was seen for 7 of 8 regions in comparisons between demented patients and age-matched controls. This atrophy was most pronounced in superior parietal (SP) regions. Decreases in parietal LCMRglc in dementia patients and SP LCMRglc in old controls were no longer significant after correction for atrophy. These results emphasize the need to consider focal atrophy effects in regional quantitative analyses of emission tomographic data.

Aged↗
PubMed1990

Multimodality imaging of a pancreatic transplant. A case report.

A 41-year-old man who had insulin-dependent diabetes mellitus from the age of 14 underwent cadaveric renal transplant in 1984. Two years later, the patient underwent pancreatic allograft transplantation. The patient did well for eight days after the operation and did not require exogenous insulin. After the eighth day, serum glucose levels rose. Multiple radiologic studies were performed to assess the possibility of graft rejection. A Tc-99m DTPA study revealed a gradual decrease in perfusion, and an In-111 oxine WBC study showed nonspecific inflammation. CT scanning and MRI displayed postsurgical anatomical relationships and excluded a peripancreatic fluid collection, but were unable to demonstrate parenchymal abnormality of the pancreas. Tests for infection proved negative. Because the decreased blood flow demonstrated by DTPA study indicated transient ischemia, the patient was treated for graft rejection and stabilized quickly.

Adult↗
PubMed1990

Radiolabeled antifibrin antibody in the detection of venous thrombosis: preliminary results.

The recent development of monoclonal antibodies against components of coagulated blood may provide new approaches to the diagnosis of venous thrombosis. Scanning with an indium-111-labeled Fab fragment of a murine monoclonal antifibrin antibody (59D8) and ascending contrast venography were performed in 33 patients. Images of the calves, popliteal fossae, thighs, and pelvis were obtained immediately, 4-6 hours, and 24 hours after injection of 2 mCi (74 MBq) of the antibody. All images were read in a blinded manner. Findings in both studies were positive in 28 patients and negative in three. In 19 patients not undergoing heparin therapy, 19 specific anatomic sites were positive on venograms and 29 were positive on antibody images (19 sites matched). In 14 patients undergoing heparin therapy, 34 sites were positive on venograms and 27 were positive on antibody images (22 sites matched). In most patients, positive results were noted within 1 hour of antibody injection. No adverse effects were noted with the antibody preparation. Preliminary data suggest that antifibrin antibody imaging is sensitive in detecting clots, is safe to use, and may have a role in diagnosing and managing venous thrombosis.

Adult↗
PubMed1990

In vivo SPECT imaging of CNS D-2 dopamine receptors: initial studies with iodine-123-IBZM in humans.

Iodobenzamide (IBZM) is a D-2 dopamine receptor antagonist. In this paper the results of Phase I clinical studies of iodine-123-(123I)IBZM in humans are reported. Preliminary imaging studies, both planar and single-photon emission tomography (SPECT), of no-carrier added [123I]IBZM in humans show specific localization in the basal ganglia of the brain. At 2 hr after an i.v. injection, the brain uptake was 3.72% of the dose, and at 20 hr later the uptake diminished to 0.7%. Radiation dosimetry calculation indicated that the radiation dose to the brain was minimum, 0.039 rad/mCi, while the large intestine wall received the highest dose, 0.28 mrad/mCi. The radiation dosimetry and pharmacology data suggest that this agent is safe for human use.

Adult↗
PubMed1990

The characterization of IBF as a new selective dopamine D-2 receptor imaging agent.

The in vivo and in vitro studies of a new iodinated benzamide analog, [125I]IBF,5-iodo-7-N-[(1-ethyl-2-pyrrolidinyl)methyl]carboxamido-2,3- dihydrobenzofuran as a potential central nervous system (CNS) D-2 dopamine receptor imaging agent were investigated. In vivo biodistribution of IBF in rat indicated that this agent concentrated in the striatum region and displayed a remarkably high target-to-nontarget ratio (striatum/cerebellum = 48 at 120 min post-injection). The in vitro binding studies suggested that IBF binds selectively to D-2 dopamine receptors with high affinity and low nonspecific binding (Kd = 0.106 +/- 0.015 nM, Bmax = 448 +/- 18.2 fmole/mg protein). Ex vivo autoradiography results in rats further confirmed the high uptake and retention of this agent in the basal ganglia region. The planar images of monkey brains (lateral view of the head) after i.v. injection of [123I]IBF clearly demonstrated that D-2 dopamine receptors can be visualized. With the excellent in vivo stability to deiodination and high target-to-nontarget ratio, [123I]IBF may be useful as a CNS D-2 dopamine receptor imaging agent for single photon emission computed tomography (SPECT) in humans.

Animals↗
PubMed1990

A new myocardial imaging agent: synthesis, characterization, and biodistribution of gallium-68-BAT-TECH.

In order to develop a new myocardial perfusion agent for positron emission tomography (PET), a new lipid-soluble gallium complex was evaluated. Synthesis, radiolabeling, characterization, and biodistribution of a unique gallium complex, [67Ga]BAT-TECH (bis-aminoethanethiol-tetraethyl-cyclohexyl), are described. The complex formation between Ga+3 and BAT-TECH ligand is simple, rapid, and of high yield (greater than or equal to 95%). This process is amenable to kit formulation. The complex has a net charge of +1 and a Ga/ligand ratio of 1:1. Biodistribution in rats shows high uptake in the heart as well as in the liver. When [68Ga] BAT-TECH was injected into a monkey, the heart and liver are clearly delineated by PET imaging, suggesting that this complex may be a possible tracer for myocardial perfusion imaging.

Animals↗
PubMed1990

Magnetic resonance imaging and scintigraphic correlation in thyroid disorders.

Thirty-nine patients (30 women and 9 men) underwent magnetic resonance imaging (MRI) and scintigraphic examinations to compare MRI evaluation qualitatively with the accepted standard of nuclear medicine diagnosis. Disorders evaluated included multinodular goiter (toxic and nontoxic), diffuse thyrotoxic states and solitary cold nodules (benign and malignant). Scintigraphy accurately detected palpable nodules and provided a gold standard against which to compare MRI findings. MRI frequently detected additional smaller nonpalpable lesions of uncertain clinical significance. High-resolution surface-coil MRI was more sensitive in detecting lesions not evident on scintigraphic images, although specificity could not be ascertained. T2-weighted images corresponded more closely to scintigraphic findings than T1. MRI provided superior anatomic detail in multiple imaging planes without any ionizing radiation exposure or need for IV contrast. MRI did not differentiate benign from malignant etiologies.

Female↗
PubMed1990

Validation studies of iodine-123-iodoamphetamine as a cerebral blood flow tracer using emission tomography.

We studied the radioisotope iodine-123-iodoamphetamine ([123I]IMP) and its performance in single-photon emission computed tomographic (SPECT) studies of cerebral blood flow (CBF). In seven normal volunteers, IMP/SPECT CBF measurements were calculated using a two-compartment model and were compared with the results of CBF measurements utilizing (O15)-H2O and positron emission tomography (PET). Calculated mean PET CBF was 57.6 ml/100 g/min while the SPECT CBF value was 47.3 ml/100 g/min. The response of IMP/SPECT CBF to alterations in arterial PaCO2 was studied in hypo-, eu- and hypercarbic subjects. SPECT CBF values showed a reactivity of 1.03 ml/100 g/min per mmHg PaCO2 change. These results show that the IMP/SPECT CBF technique may be used for quantitative imaging of CBF in man. They provide further support for IMP as a CBF tracer.

Amphetamines↗
PubMed1989

Positron emission tomography to study the effect of eye closure and optic nerve damage on human cerebral glucose metabolism.

We used 18F-2-fluoro-2-deoxyglucose and positron emission tomography to evaluate the effect of visual deprivation on brain glucose metabolism. In experiment 1, we compared local cerebral metabolic rates for glucose in seven normal volunteers studied with eyes closed to 11 age- and sex-matched normal volunteers studied with eyes open. Whole brain metabolism was similar in the two groups, and region/whole brain analysis of metabolic data showed that metabolism in the calcarine posterior cortex was decreased by 14% (P less than .05) with eye closure. Glucose metabolism in other regions was not different between the two groups. In experiment 2, we compared glucose metabolism in six patients with severe bilateral optic neuropathies to 12 age- and sex-matched normal controls. Whole brain glucose metabolism was unchanged in the optic neuropathy group compared to controls. However, statistically significant reductions in glucose metabolism in the optic neuropathy group were found in anterior calcarine cortex (17%), posterior calcarine cortex (27%), peristriate cortex (27%), and lateral occipital cortex (15%). The metabolic effects of damage to the pregeniculate visual system went well beyond those of simple eye closure.

Adolescent↗
PubMed1989

Effects of collateral blood vessel ligation and electrical conditioning on blood flow in dog latissimus dorsi muscle.

Utilization of skeletal muscle as a myocardial substitute requires it to undergo two major modifications: mobilization to the site of action and adaptation to continuous activity. We have examined the effects of collateral blood vessel ligation, which would accompany mobilization, on blood flow in control and electrically conditioned canine latissimus dorsi (LD) muscle. Blood flows were measured at rest and during a vigorous isometric fatigue test. In 22 control muscles, electrical stimulation during the fatigue test resulted in a sevenfold increase in muscle blood flow (0.26 +/- 0.18 ml/g/min at rest, 1.69 +/- 0.84 ml/g/min during stimulation). No difference was detected in flow to distal and proximal portions of the muscle. In three muscles where collateral vessels were ligated immediately before measurement of blood flow, flow in the proximal portion of the muscle was not significantly different from control, but in the distal portion, stimulation failed to elicit an increase in flow (0.12 +/- 0.13 ml/g/min at rest, 0.16 +/- 0.07 ml/g/min during stimulation). In animals allowed a 3-week recovery period following collateral vessel ligation, stimulation-induced increases in blood flow were detected but remained lower than control. Muscles which had been conditioned by continuous electrical stimulation for 6-7 weeks at 2 or 10 Hz generated less peak isometric tension than controls (peak tension = 4.5 +/- 1.7 kg control, 2.4 +/- 0.7 kg following 2 Hz conditioning, 1.6 +/- 0.4 kg following 10 Hz conditioning). However, these muscles demonstrated an increased resistance to fatigue.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗