Regional myocardial substrate uptake in hypertensive rats: a quantitative autoradiographic measurement.

Severe hypertension causes global and regional changes in myocardial perfusion and substrate utilization. Regional perfusion and fatty acid utilization were evaluated by dual-tracer autoradiography in normotensive and hypertensive rats of the Dahl strain. The regional distributions of perfusion and fatty acid utilization were homogeneous in normotensive rats. Severe hypertension was associated with a homogeneous pattern of regional perfusion, but fatty acid utilization was focally decreased in the free wall of the left ventricle. The decrease in fatty acid uptake was associated with a concomitant increase in glucose utilization. These findings suggest that severe hypertension is associated with uniform myocardial perfusion and focal alterations in the substrates used for the performance of myocardial work.

Migration inhibition factor activity in sera of patients with chronic lymphatic leukemia.

Migration inhibition factor (MIF) activity, expressed as a migration index, was studied in the sera of 48 chronic lymphatic leukemia (CLL) patients and 48 healthy controls. MIF activity was detected in the sera of 50% of the CLL patients. The medical condition of patients in advanced clinical stages (III and IV) and with detectable MIF activity was more stable (after 18-mo follow-up) than was that of the patients in advanced stages but without detectable MIF activity. No relationship was found between the clinical stage of the disease, absolute lymphocyte count, and MIF activity.

Hypersensitivity pneumonitis induced by nalidixic acid.

Interstitial pneumonitis developed in a patient one week after therapy with nalidixic acid was initiated. The causal association between the drug and the lung disease is based on the temporal relationship, an increased eosinophil count in both peripheral blood and fluid obtained by bronchoalveolar lavage, a positive migration inhibitory factor test with nalidixic acid, and exclusion of other causes. This is, to the best of our knowledge, the first report of a pulmonary hypersensitivity reaction to nalidixic acid.

Evaluation of prajmalium-induced cholestasis by immunologic tests.

Cholestatic jaundice developed in four patients after the administration of prajmalium bitartrate. The clinical, histologic, ultrastructural, and immunologic findings were determined. In all patients, the clinical and morphologic features indicated idiosyncrasy. Two antibodies distributed in a granular pattern along the bile canaliculi were detected by immunofluorescence in all patients. In one patient, autoimmune markers were found in the serum, and in two instances, the migration-inhibition factor assay against the offending drug was found to be positive. The data support the concept that immunologic processes may participate in the production of the cholestatic syndrome.

Abnormal immune response to brain tissue antigen in the syndrome of autism.

Cell-mediated immune response to human myelin basic protein was studied by the macrophage migration inhibition factor test in 17 autistic patients and a control group of 11 patients suffering from other mental diseases included in the differential diagnosis of the syndrome of autism. Of the 17 autistic patients, 13 demonstrated inhibition of macrophage migration, whereas none of the nonautistic patients showed such a response. The results indicate the existence of a cell-mediated immune response to brain tissue in the syndrome of autism.

Cell-mediated immunity to polio and HLA antigens in amyotrophic lateral sclerosis.

Cell-mediated immunity to poliovirus was demonstrated in 21 of 33 patients suffering from amyotrophic lateral sclerosis (ALS), whereas no response to poliovirus was found in patients suffering from other neurologic disorders or in healthy controls. Three of the severe bulbar cases produced a migration inhibition factor (MIF) in the presence of poliovirus, although skin tests to common antigens were negative. An increased incidence (46 percent) of HLA-A3 was found in patients with amytrophic lateral sclerosis. Nine of the 13 patients with HLA-A3 antigen also had a positive index of MIF to poliovirus. These findings suggest a strong linkage between HLA-A3 and poliovirus in the pathogenesis of amyotrophic lateral sclerosis.

Pharmacokinetics of fleroxacin as studied by positron emission tomography and [18F]fleroxacin.

A new method of tracing the disposition of fleroxacin was tested in infected and noninfected animals in an effort to develop a technique that might be applicable in humans. [18F]fleroxacin was synthesized and shown to be identical physically, chemically, and in its antimicrobial activity to the commercially produced product. Tracer amounts of [18F]fleroxacin were coinjected with a pharmacologic dose of unlabeled drug (10 mg/kg) into normal mice, rats with focal thigh infection due to Escherichia coli, and normal and infected rabbits. The rats and mice were killed at fixed time intervals after injection, and the concentration of drug was determined by radioactive counting in a well-type counter; the rabbits were studied both by this method and by positron emission tomographic (PET) imaging. These studies validated the reliability of the new approach and suggested that it could be applied safely to humans. In all three animal species studied, delivery of [18F]fleroxacin to most tissues was rapid, with the notable exception of the brain. Accumulation of drug in infected thigh muscle was similar to that in normal muscle. The concentrations of drug reached in various tissues suggest that fleroxacin will be particularly useful in the treatment of gastrointestinal, urinary tract, hepatobiliary, and skeletal infections and that it shows promise for the treatment of lung and soft tissue infection. The minimal concentrations of drug delivered to the brain should decrease the occurrence of central nervous system toxicity with this particular fluoroquinolone.

Synthesis and biologic distribution of mercapto derivatives of palmitic acid.

Mercapto derivatives of palmitic acid are capable of binding 99mTc. Based on the hypothesis that 99mTc-labeled palmitic acid derivatives would behave biologically like palmitic acid and thus could be used as myocardial imaging agents, three mercaptopalmitic acid derivatives have been prepared. The synthesis of 2-mercaptopalmitic acid, 2-mercapto-1,16-hexadecanedioic acid, and 16-mercaptopalmitic acid was accomplished by reaction of the corresponding bromo compound with thiourea. The 35S-labeled compounds and [16-14C]palmitic acid were evaluated in rats with a heat-inflicted myocardial infarction to study the effect of the introduction of the mercapto group. The organ distribution of 2-[35S]mercaptopalmitic acid was most similar to that of [16-14C]palmitic acid.

Preparation and characterization of two complexes of technetium with 2-mercaptocarboxylic acids.

We have synthesized the tetraphenylarsonium salts of oxotechnetium(V)bis-(2-mercaptopropionate) and oxotechnetium(V)bis-(2-mercaptohexadecanoate) containing macromolar quantities of the long-lived isotope technetium-99. The compounds were investigated by elemental analysis, paper electrophoresis, and infrared and ultraviolet-visual spectroscopy, proton nuclear magnetic resonance, and field-desorption mass spectrometry. The findings suggest that the technetium atom is coordinated by two sulfur and three oxygen atoms in a square pyramid, the two sulfur atoms and two of the oxygen atoms forming the base and the third oxygen atom the apex. The carboxyl oxygen coordinated to technetium will not be available for binding in vivo. This factor should be considered in the design of technetium 99m-labeled radiopharmaceuticals containing a mercapto group alpha to a carboxyl group.

Synthesis and biologic evaluation of 1-[11C]-3,3-dimethylheptadecanoic acid.

1-[11C]-3,3-dimethylheptadecanoic acid [( 11C]DMHDA) has been prepared for evaluation as a potential myocardial metabolism indicator based on an expected intrinsic stability toward beta-oxidative metabolic processes. Synthesis of this novel branched-chain fatty acid was accomplished by copper-catalyzed addition of tetradecylmagnesium bromide to diethylisopropylidenemalonate. Subsequent saponification and decarboxylation afforded 3,3-dimethylheptadecanoic acid (DMHDA) that was converted to the corresponding alkyl bromide by means of a modified Hunsdiecker reaction. Carboxylation of 2,2-dimethylhexadecylmagnesium bromide with 11CO2 gave [11C]DMHDA. Carbon-11 DMHDA showed moderate myocardial uptake in fasted rats, albeit lower than that reported for the 3-monomethyl analog. Considerable washout of radioactivity from the heart was also observed over the first 30 min postinjection. Imaging in dogs likewise showed disappointing heart uptake with much higher localization in the lung. These data suggest that gem-dimethyl substitution of the beta-position in long chain fatty acids is not only insufficient for enhanced myocardial uptake and retention, but also, may be deleterious when compared with beta-monomethylation.

Myocardial extraction of 1-[11C] betamethylheptadecanoic acid.

UNLABELLED: Betamethylheptadecanoic acid (BMHA) is a branched chain fatty acid analog that is transported into myocardial cells by the same long chain fatty acid carrier protein mechanism as natural fatty acids, but cannot be completely catabolized and accumulates in the tissue. Thus, 11C-labeled BMHA is a useful tracer for the noninvasive evaluation of myocardial fatty acid utilization by positron emission tomography (PET). METHODS: As a prelude to PET studies, the metabolism of BMHA was studied by classical techniques. We measured the net extraction fraction (En) of 1-[11C]-beta-R,S-methylheptadecanoic acid (1-[11C]BMHA) and compared it to that of natural fatty acids in dogs, using arterial/venous measurements and a mathematical model. Two groups of conditioned dogs were studied. In the first group, measurements were made under fasting (normal control) conditions and in the second group, measurements were made during glucose and insulin infusion. Myocardial blood flow, and the extraction/utilization of other substrates (glucose, oxygen and lactate) were also measured. RESULTS: For natural fatty acids in the basal state, En(FA) was 0.335. After glucose/insulin infusion, this value decreased to 0.195. The 1-[11C]BMHA showed a similar decrease in En(BMHA) from 0.220 in the control group to 0.100 in the group treated with glucose/insulin infusion. Preliminary PET studies with 1-[11C]BMHA verified the validity of performing these measurements noninvasively. CONCLUSION: The results of these studies indicate that rates of fatty acid metabolism in the myocardium can be determined from steady-state concentrations of 1-[11C]BMHA.

Beta-methyl[1-11C]heptadecanoic acid: a new myocardial metabolic tracer for positron emission tomography.

We have tagged heptadecanoic acid with C-11 at the carboxyl group and have inserted a methyl radical in the beta position to inhibit beta oxidation of the fatty acid; we have then explored the tracer's potential as an indicator of myocardial metabolism for use with the positron tomograph. In this preliminary evaluation, biodistribution studies were made in rats and dogs, and imaging of normal and infarcted dogs was performed. At 30 min the tissue distribution studies in rats and dogs showed, respectively, 1.9% and 8.3% uptake in the heart. Sequential images of the canine heart exhibited a remarkable uptake, peaking at 16-18 min and retaining the same level of activity over the one-hour study period. Images of the heart after LAD ligation showed an area of diminished uptake corresponding to the region of infarction. Thus this agent has the basic properties required for potential use in the assessment and quantitation of free fatty-acid metabolism in the heart in a manner similar to the measurement of glucose metabolism in the brain with 2-[18F]fluoro-3-deoxy-D-glucose.

Metabolism of beta-methyl-heptadecanoic acid in the perfused rat heart and liver.

The metabolism of beta-methyl-[1-14C]heptadecanoic acid, a potential myocardial imaging agent, was investigated in perfused hearts and livers from rats. Hepatic uptake is approximately 4.5 times greater than cardiac uptake. In the heart, 66% of beta-methyl-heptadecanoic acid metabolism occurs via omega-oxidation, 33% by esterification and less than 1% via alpha-oxidation. In contrast, 53% of hepatic metabolism of beta-methyl-heptadecanoic acid occurs via alpha-oxidation, 27% via omega-oxidation, and 20% via esterification. Perfusion of hearts and livers with concentrations of beta-methyl-heptadecanoic acid 100 to 1000 times greater than that used for myocardial imaging does not alter any of the physiological and biochemical parameters measured. In the perfused liver, 3-methyl-[1-14C]glutarate was identified as the principal hydrosoluble catabolite of beta-methyl-heptadecanoic acid.

[11C]MPTP: a potential tracer for Parkinson's disease research in laboratory animals.

[11C]-1-Methyl-4-phenyl-1,2,5,6-tetrahydropyridine ([11C]MPTP), a compound producing parkinson-like symptoms in several species, has been synthesized and purified in sufficient activity to obtain tomographic images in the monkey. Biodistribution data has also been obtained in rats. Carbon-11-labeled MPTP could be used as a probe to study the pharmacokinetics of the compound under various research conditions in animals. Because of its neurotoxicity, the compound is not intended for use in humans.

Cell mediated immunity to human myelin basic protein in Vogt-Koyahagi-Harada syndrome.

An immunological basis for neurological involvement in Vogt-Koyanagi-Harada syndrome was sought by means of the migration-inhibition factor technique with human myelin basic protein. The test was carried out in four patients who had recent manifestations of the syndrome, two of whom were evaluated both before and after initiation of steroid treatment; in one patient 4 years after recovery from the syndrome; in three patients having uveitis of other causes, and in 12 healthy controls. The results were positive in all four patients who had recent manifestations, whereas they were negative in all the others. This finding may constitute evidence of a cell-mediated immunity toward components of the nervous system in this disease entity.

Inhibition of macrophage migration by choroidal malignant melanoma-associated antigens in patients with unveal melanoma.

The specific cell-mediated immunity of the lymphocytes of eight patients with choriodal malignant melanoma (MM) to four extracts of choroidal MM-associated antigens was tested with the aid of the MIF technique. Seven of the patients with choroidal MM responded to at least one of the four extracts used, whereas patients with choroidal nevus or carcinoma as well as healthy controls did not respond to any of the MM choroidal extracts. There was no response to iris extracts obtained from the enucleated eyes with MM in any of the subjects tested.

Detection of dopaminergic cell loss and neural transplantation using pharmacological MRI, PET and behavioral assessment.

We demonstrate the use of magnetic resonance imaging (MRI) for detection of neurotransmitter stimulation using the dopamine transporter ligands amphetamine and CFT (2beta-carbomethoxy-3beta-(4-fluorophenyl)tropane) as pharmacological challenges. We demonstrate that the unilateral loss of a hemodynamic response to either amphetamine or CFT challenge by unilateral 6-hydroxydopamine lesioning is restored by transplantation of fetal dopamine neurons in the striatum. The time course for the hemodynamic changes parallels the time courses for dopamine release, measured by prior microdialysis studies, and also for the rotational behavior in the unilaterally lesioned animals. Transplantation of the fetal cells results in hemodynamic time courses after CFT or amphetamine challenges at the graft site that are identical to those induced both before transplantation and on the intact contralateral side. The transplantation also results in complete behavioral recovery. The spatial extent of the dopaminergic recovery in the lesioned striatum is the same when measured using either PET of tracer levels of [11C]CFT binding or MRI. These results show great promise for the application of pharmacological MRI for application to studies of dopamine cell loss and potential recovery in Parkinson's disease.

Macrophage migration inhibition factor (MIF) in drug eruption.

A controlled study was conducted to evaluate the macrophage migration inhibition factor test as a diagnostic aid in 50 patients with drug eruption. Two groups of patients served as controls: group A, 110 patients being treated with drugs without known cutaneous adverse reactions, and group B, 15 patients suffering from dermatologic disorders unrelated to drugs being taken. Positive macrophage migration inhibition factor responses were found toward a variety of drugs in 35 (70%) of the patients with drug eruptions, with no relation to the type of eruption or the duration of drug intake. The percentage of positive macrophage migration inhibition factor responses toward drugs in the patients with drug eruptions was higher than that in the two control groups (4.5% and 6.7%, respectively). The percentage of positive macrophage migration inhibition factor responses recorded for clinically "suspected" drugs was significantly higher than that recorded for the "nonsuspected" drugs.

Tissue pharmacokinetics of fleroxacin in humans as determined by positron emission tomography.

The delivery of fleroxacin, a new broad-spectrum fluoroquinolone, to the major organs of the body was studied in 12 normal human volunteers (nine men and three women), utilizing positron emission tomography (PET). Following the infusion of 20 mCi of [(18)F]fleroxacin in conjuction with a standard therapeutic dose of 400 mg, images were acquired over 8 h. Beginning the next day, the subjects received unlabeled drug at a dose of 400 mg/day for 3 days, with a repeat PET study on the fifth day. Fleroxacin is distributed widely throughout the body, with the notable exception of the central nervous system, with stable levels achieved within 1 h after completion of the infusion. Especially high peak concentrations (18 mug/g) were achieved in the kidney, liver, lung myocardium, and spleen. The mean plateau concentrations (2-8 h post-infusion, mug/g) were: brain 0.83; myocardium, 4.53; lung, 5.80, liver, 7.31; spleen, 6.00; bowel, 3.53; kidney, 8.85; bone, 2.87; muscle, 4.60; prostate, 4.65; uterus, 3.87; breast, 2.68; and blood, 2.35. Repetitive dosing had no significant effect on the pharmacokinetics of the drug. Since the MIC(90)'s of the family Enterobacterioaceae and Neisseria gonorrhoeae are <2 mug/ml, with the great majority of the individual species 1 mug/ml, these results suggest that a single daily dose of 400 mg of fleroxacin should be effective in the treatment of infections such as urinary tract infection and gonorrhea.

Cell-mediated immunity to human myelin basic protein in schizophrenic patients.

Cell-mediated immune response to myelin human basic protein was studied by the macrophage migration inhibition test in patients suffering from schizophrenia. Eighteen out of 32 patients with chronic schizophrenia demonstrated human basic protein-induced inhibition of the migration index, while 4 out of 41 acute schizophrenics showed an inhibition of macrophage migration.