Diagnostic accuracy of 99mTc-sestamibi breast imaging: multicenter trial results.

UNLABELLED: Although mammography is well established as a first-line tool for breast cancer screening and detection, efforts to develop complementary procedures continue. Observation of 99mTc-sestamibi tumor uptake provided the impetus for its evaluation as an adjunctive technique. This trial's objectives were to determine in a multicenter trial the diagnostic accuracy of 99mTc-sestamibi in women with suspected breast cancer and to investigate factors influencing diagnostic accuracy. METHODS: Our multicenter trial enrolled 673 women (387 with nonpalpable abnormalities; 286 with palpable abnormalities) scheduled for excisional biopsy or mastectomy. Blinded and unblinded interpretations of scintigraphic images were compared with core laboratory established histopathologic diagnoses to define the diagnostic accuracy of 99mTc-sestamibi breast imaging. RESULTS: Blinded readers' diagnostic accuracy was 78%-81%. Inter-reader agreement was excellent, ranging from 95% to 100% (kappa = 0.82-0.99). Overall institutional sensitivity and specificity for 99mTc-sestamibi breast imaging were 75.4% and 82.7%, respectively. In this population with a 40.1% disease prevalence, the positive predictive value was 74.5% and the negative predictive value was 83.4%. The negative predictive value was 94% in patients with a 40% or lower mammographic likelihood of breast cancer. Sensitivity was higher for palpable abnormalities; specificity was higher for nonpalpable abnormalities. Sensitivity was decreased for tumors <1 cm in largest dimension but appeared not to be affected by patient's age. CONCLUSION: As an adjunct to current procedures, 99mTc-sestamibi breast imaging may contribute to patient management decisions in selected populations, including women with dense breasts, mammographically indeterminate lesions >1 cm, and palpable abnormalities.

Early dipyridamole (99m)Tc-sestamibi single photon emission computed tomographic imaging 2 to 4 days after acute myocardial infarction predicts in-hospital and postdischarge cardiac events: comparison with submaximal exercise imaging.

BACKGROUND: Because of its brief hemodynamic effects and minor effect on determinants of myocardial oxygen demand, vasodilator stress myocardial perfusion imaging (MPI) can be applied very early after acute myocardial infarction (AMI) for risk stratification, allowing management decisions to be made earlier and thus potentially shortening hospitalization stays, reducing costs, and preventing early cardiac events. This multicenter randomized trial compared the prognostic value of early dipyridamole MPI and standard predischarge submaximal exercise MPI in patients who presented with AMI. METHODS AND RESULTS: Patients who presented with their first AMI (n=451) were randomized in a 3:1 ratio to undergo either both an early (day 2 to 4) dipyridamole (99m)Tc-sestamibi MPI study and a predischarge (day 6 to 12) submaximal exercise (99m)Tc-sestamibi MPI study or only the predischarge study. Multivariate predictors of in-hospital cardiac events included nuclear imaging summed stress and summed reversibility scores and peak creatine kinase. For postdischarge cardiac events, multivariate predictors in patients undergoing dipyridamole MPI included only the summed stress, reversibility, and rest imaging scores and anterior MI. For a given summed stress score, the interaction of reversibility score further improved the predictive value. Dipyridamole MPI showed better risk stratification than submaximal exercise MPI. CONCLUSIONS: Dipyridamole MPI very early after MI predicts early and late cardiac events, with superior prognostic value compared with submaximal exercise imaging. The extent and severity of the stress defect and reversibility of the defect were the most important predictors of cardiac death and recurrent MI. This technique can allow management decisions to be made earlier with regard to AMI patients and could have important economic impact if applied widely.

Safety of early intravenous dipyridamole technetium 99m sestamibi SPECT myocardial perfusion imaging after uncomplicated first myocardial infarction. Early Post MI IV Dipyridamole Study (EPIDS).

We assessed the safety of early (2 to 4 days) intravenous dipyridamole infusion in conjunction with technetium 99m sestamibi tomographic myocardial perfusion imaging in patients with first myocardial infarction (MI). Early risk stratification with myocardial perfusion imaging of patients after acute MI may be useful to identify patients who either require further evaluation or may be safely discharged. Because of minimal hemodynamic effects, intravenous dipyridamole may be a safe means of producing hyperemia for myocardial perfusion imaging. Stable patients with first acute MI who met entry criteria were randomized (3:1) to either intravenous dipyridamole infusion (0.56 mg/kg over a 4-minute period) 48 to 96 hours after onset of symptoms or a control (no test) group. Adverse cardiac events (unstable angina, recurrent MI, or cardiac death) were evaluated during and 24 hours after the dipyridamole infusion and during the corresponding 24 hours for the control group. Two hundred eighty-four patients received dipyridamole infusion a mean time of 3.3 +/- 0.7 days after MI. There were no adverse clinical events either during or immediately after the infusion. During the 24 hours after infusion, three patients had symptoms of unstable angina pectoris, one patient had a recurrent MI, and no patients died. The earliest event occurred 4.2 hours after the dipyridamole infusion. Three patients had unstable angina pectoris, whereas no patients had either recurrent MI or died in the control group. There were no statistically significant differences between the two groups. In a multicenter trial, dipyridamole infusion administered early after the first acute MI resulted in no increased evidence of cardiac events either immediately or 24 hours after the procedure compared with a control group. Therefore intravenous dipyridamole can be safely used as a pharmacologic vasodilator for myocardial perfusion imaging soon after uncomplicated MI.

Anti-inflammatory and safety profile of DuP 697, a novel orally effective prostaglandin synthesis inhibitor.

DuP 697 (5-bromo-2[4-fluorophenyl]-3-[4-methylsulfonylphenyl]-thiophene) is a potent inhibitor of paw swelling in nonestablished and established adjuvant arthritis in rats (ED50 = 0.03 and 0.18 mg/kg/day, respectively). DuP 697 had no effect on phenylquinone writhing in rats (ED50 greater than 100 mg/kg), but was analgetic against inflammation-related pain in the Randall-Selitto assay (ED30 = 3.5 mg/kg) and was a very potent antipyretic agent (ED50 = 0.05 mg/kg). The drug was not ulcerogenic in rats at single doses up to 400 mg/kg. DuP 697 (5 mg/kg i.v.) did not alter renal blood flow or the renal vascular response to angiotensin II in furosemide-pretreated, volume-depleted rats. In contrast, indomethacin (5 mg/kg i.v.) decreased renal blood flow and potentiated the renal vascular response to angiotensin II in these animals. DuP 697 was a moderate inhibitor of bull seminal vesicle prostaglandin (PG) synthesis (IC50 = 2.4 X 10(-5) M) and a potent inhibitor of rat brain PG synthesis (IC50 = 4.5 X 10(-6) M) but was ineffective against rat kidney PG synthesis (IC50 7.5 X 10(-5) M). These differential effects of DuP 697 on PG synthesis by various tissues may account for its high potency as an anti-inflammatory and antipyretic agent and its minimal toxicity profile.

Pharmacokinetic evaluation of technetium-99-metallothionein-conjugated mouse monoclonal antibody B72.3 in rhesus monkeys.

These studies were conducted to determine the biodistribution and pharmacokinetics of [99mTc]metallothionein-conjugated B72.3 ([ Tc]MT-B72.3) in Rhesus monkeys (Macaca mulatta) that were performed as part of the preclinical evaluation of [Tc]MT-B72.3. The B72.3-MT conjugate was studied at three doses of B72.3 ranging from 0.03 mg/kg to 1 mg/kg to determine whether a relationship existed between the dose of total antibody administered intravenously and the biodistribution and clearance of the radiolabeled protein. Results indicated that [Tc]MT-B72.3 distributes rapidly to central body cavity organs and that there was no difference in the rate of blood elimination for the three doses of B72.3 studied. The terminal phase of blood elimination was found to be 26.2 +/- 6.1 hr for the combined groups of monkeys. Approximately one-half of injected 99mTc activity was recovered in the urine within 24 hr. A second purpose of these studies was to evaluate the overall immunogenicity of the mouse monoclonal B72.3 IgG1 antibody in Rhesus monkeys. These results demonstrated that a single i.v. exposure to mouse monoclonal B72.3 at doses of 0.3 mg/kg or greater elicited antibody production to B72.3 in Rhesus monkeys within 3 wk. Analysis of [Tc]MT-B72.3 biodistribution and clearance in monkeys with circulating levels of antibodies to B72.3 (immunized monkeys) revealed that the liver was the primary site of clearance of the presumed immune complex and that blood elimination was greatly accelerated.

Thirteen-week toxicity study of n-hexane in B6C3F1 mice after inhalation exposure.

B6C3F1 mice were exposed to n-hexane 6 h/day, 5 days/week for 13 weeks at concentrations of 0, 500, 1000, 4000, and 10,000 ppm and at 1000 ppm 22 h/day, 5 days/week for 13 weeks (1000C group). Toxicological endpoints assessed included clinical signs, body and organ weight changes, gross and histopathology, neuropathology, and a battery of neurobehavioral tests. All mice survived the treatment. Exposure-related effects of n-hexane included sneezing at 10,000 ppm and body weight gain depression at 1000C and 10,000 ppm. Histopathologic changes included mild inflammatory, erosive and regenerative lesions in the olfactory and respiratory epithelium of the nasal cavity at 1000C, 4000, and 10,000 ppm. The only neurobehavioral parameter affected was a decrease in locomotor activity in female mice at 1000C and 10,000 ppm. In teased fiber preparations of tibial nerve, paranodal axonal swellings were observed at 1000C or at 10,000 ppm, but not in the control groups. The severity of the peripheral nerve lesion was mild. These studies show that n-hexane has minimal toxicity to the nervous system and respiratory system of mice.

Toxicology and pathology of methyl bromide in F344 rats and B6C3F1 mice following repeated inhalation exposure.

The toxicity of methyl bromide was studied in male and female F344 rats and B6C3F1 mice exposed by inhalation to 160 ppm methyl bromide or air 6 hr/day, 5 days/week for up to 6 weeks. The animals were killed after 3, 10, or 30 exposure days, or when 50% mortality was observed in any group. Only female rats survived the entire 30 exposure days at 160 ppm methyl bromide with less than 50% mortality. There were clear species- and sex-related differences in susceptibility of specific organs to methyl bromide. Primary target organs were the brain, kidney, nasal cavity, heart, adrenal gland, liver, and testis. In rats, neuronal necrosis occurred in the cerebral cortex, hippocampus, and thalamus of the brain whereas in mice neuronal necrosis occurred primarily in the internal granular layer of the cerebellum. Nephrosis occurred in all exposed mice, but not rats, and was likely a major cause of moribundity and death. Necrosis of the olfactory epithelium was more severe and extensive in rats than mice. Myocardial degeneration occurred in male and female rats and to a lesser degree in male mice. There was atrophy of the inner zone of the adrenal cortex in female mice and cytoplasmic vacuolation of the adrenal cortex in rats. Testicular degeneration occurred in rats and mice. The target organ specificity of methyl bromide is similar to that of methyl chloride, suggesting that the two monohalomethanes may have a common mechanism of action.

Conjugation of metallothionein to a murine monoclonal antibody.

A method of conjugation of the metal-binding protein, metallothionein, to an anticarcinoma murine monoclonal antibody, B72.3, and its F(ab')2 fragment has been developed utilizing the heterobifunctional crosslinking reagent, succinimidyl 4-(N-maleimidomethyl)-cyclohexane 1-carboxylate. This crosslinking reagent is first reacted with the free amines on the immunoglobulin. After removal of unreacted crosslinker, conjugation is affected through a sulfhydryl group on metallothionein. Under the conditions employed all immunoglobulin aggregates contained metallothionein. The degree of undesired aggregation is directly proportional to the number of metallothioneins attached to the immunoglobulin. This aggregation can be controlled by the amount of crosslinker and metallothionein presented to the immunoglobulin. The immunoglobulin conjugate retains full immunoreactivity and can be readily purified from the unreacted metallothionein and high molecular weight aggregates. The metallothionein-B72.3 conjugate functions as an efficient and stable chelator of radiometals. Thus metallothionein-monoclonal antibody conjugates have potential utility in cancer diagnosis and therapy.

The impact of inhaled acrolein on hypertension-sensitive and resistant rats.

The Dahl selected rat lines, one susceptible to salt-induced hypertension (DS) and the other resistant to salt-induced hypertension (DR), were subchronically exposed to filtered air, 0.4, 1.4, or 4.0 ppm acrolein. All of the DS rats exposed to 4.0 ppm acrolein died within the first 11 days, while 60% of the DR animals survived. Neither dose dependent blood pressure changes nor altered behavioral characteristics were evident following acrolein exposure. Exposure to 4.0 ppm acrolein increased the level of several serum enzymes. This concentration of acrolein also led to pulmonary edema and a significant increase in lung connective tissue. There was a marked difference in the pulmonary pathology observed in DS and DR rats exposed to 4.0 ppm acrolein. The lungs of the DS rats exhibited severe airway epithelial necrosis with edema and hemorrhage, while surviving DR rats primarily showed a proliferative change. Following exposure to 0.4 to 1.4 ppm acrolein, both rat lines displayed similar pathologic change. Epithelial hyperplasia and/or clusters of macrophages were usually found near terminal bronchiolar areas. These findings suggest that further investigation of the physiopathologic sensitivity of the DS rat line may elucidate a model for investigating the underlying characteristics of stress susceptible populations.

Preparation and antiarthritic and analgesic activity of 4,5-diaryl-2-(substituted thio)-1H-imidazoles and their sulfoxides and sulfones.

A series of 4,5-diaryl-2-(substituted thio)-1H-imidazoles was synthesized and evaluated as antiinflammatory and analgesic agents in the rat adjuvant induced arthritis assay and the mouse phenyl-p-benzoquinone writhing (PQW) assay. Several analogues were found to be more potent than phenylbutazone and indomethacin. Structure-activity relationships are discussed. One of the compounds, 4,5-bis(4-fluorophenyl)-2-[(1,1,2,2-tetrafluoroethyl)-sulfonyl]-1H- imidazole (8d, tiflamizole), was found to be 8 times as potent as indomethacin in the rat adjuvant induced arthritis assay and is presently undergoing clinical trial as an antiarthritic drug.

Selected responses of hypertension-sensitive and resistant rats to inhaled acrolein.

The Dahl selected rat lines, one susceptible to salt-induced hypertension (DS) and the other resistant to salt-induced hypertension (DR), were exposed to filtered air, 0.4, 1.4, or 4.0 ppm acrolein for 6 h/day, 5 days/week for 62 days. All of the DS rats exposed to 4.0 ppm acrolein died within the first 11 days, while 60% of the DR animals survived the duration of the study. Neither dose dependent blood pressure changes nor altered behavioral characteristics were evident in either rat strain following acrolein exposure. Exposure to 4.0 ppm acrolein increased the level of several serum enzymes in the DR rats which survived. This concentration of acrolein also led to pulmonary edema and a significant increase in lung connective tissue in these animals. There was a marked difference in the pulmonary pathology observed in DS and DR rats exposed to 4.0 ppm acrolein. The lungs of moribund DS rats exhibited severe airway epithelial necrosis with edema and hemorrhage, while surviving DR rats primarily showed a proliferative change. Following exposure to 0.4 and 1.4 ppm acrolein, both rat lines displayed similar pathologic changes. Epithelial hyperplasia and/or clusters of macrophages were usually found near terminal bronchiolar areas. These findings suggest that further investigation of the physiopathologic sensitivity of the DS rat line may elucidate a model for investigating the underlying characteristics of stress susceptible populations.

Psychobiology of experimental hypertension: evaluation of the Dahl rat lines.

The Dahl salt-sensitive (DS) and salt-resistant (DR) rat lines were selectively bred to show opposite genetically determined blood pressure responses to excess sodium chloride ingestion. These animals have provided significant anatomical, physiological, and biochemical data concerning the pathological mechanisms of experimental hypertension. Research is also being conducted to determine the relevance of psychobiological and behavioral variables in these two lines. The rationale for the selection and maintenance of the Dahl model and the physiological, biochemical, and behavioral characteristics which distinguish DS and DR rats are presented. Although originally developed for the study of salt-induced hypertension, special attention is given to the application of this animal model in behavior genetic research, stressing its inherent advantages and limitations. The use of the Dahl model in psychobiological studies and the utility of the model for future behavioral, genetic, and psychophysiological research are also detailed.

Age, sex and genotype effects on stimulus exploration and locomotor activity in young mice.

Age and sex effects on stimulus exploration and locomotor activity were investigated in three genetic stocks of mice. Three measures of exploratory behavior and one measure of locomotor activity were recorded in an arena testing situation. The results showed that measures requiring locomotor activity are more affected by differences in age and sex than measures of stimulus exploration. The results are discussed in terms of the previously established genetic models of stimulus exploration and activity.