Subacute administration of both methcathinone and manganese causes basal ganglia damage in mice resembling that in methcathinone abusers.

An irreversible extrapyramidal syndrome occurs in man after intravenous abuse of "homemade" methcathinone (ephedrone, Mcat) that is contaminated with manganese (Mn) and is accompanied by altered basal ganglia function. Both Mcat and Mn can cause alterations in nigrostriatal function but it remains unknown whether the effects of the 'homemade' drug seen in man are due to Mcat or to Mn or to a combination of both. To determine how toxicity occurs, we have investigated the effects of 4-week intraperitoneal administration of Mn (30 mg/kg t.i.d) and Mcat (100 mg/kg t.i.d.) given alone, on the nigrostriatal function in male C57BL6 mice. The effects were compared to those of the 'homemade' mixture which contained about 7 mg/kg of Mn and 100 mg/kg of Mcat. Motor function, nigral dopaminergic cell number and markers of pre- and postsynaptic dopaminergic neuronal integrity including SPECT analysis were assessed. All three treatments had similar effects on motor behavior and neuronal markers. All decreased motor activity and induced tyrosine hydroxylase positive cell loss in the substantia nigra. All reduced 123I-epidepride binding to D2 receptors in the striatum. Vesicular monoamine transporter 2 (VMAT2) binding was not altered by any drug treatment. However, Mcat treatment alone decreased levels of the dopamine transporter (DAT) and Mn alone reduced GAD immunoreactivity in the striatum. These data suggest that both Mcat and Mn alone could contribute to the neuronal damage caused by the 'homemade' mixture but that both produce additional changes that contribute to the extrapyramidal syndrome seen in man.

Radiolabeled Sugars Used for PET and SPECT Imaging.

There are new efforts to develop "sugar" probes for molecular imaging focusing on human clinical studies. Radiolabeled carbohydrates are used as substrate probes for studying specific processes in tissues and organisms. The best application case is 2-Deoxy-2-[18F]fluoro-D-glucose (18F-FDG), which is incorporated by cancer cells. The introduction of ltF-FDG has advanced enormously human Positron Emission Tomography (PET). This review focuses on the importance of 18FFDG and other sugars as imaging probes in PET and Single Photon Emission Computed Tomography (SPECT) imaging. In conclusion, new radiolabeled molecules that can be used as radiopharmaceuticals also would possibly help in the treatment of cancer cells in human patients.

Differential Clearance of Rat and Human Bone Marrow-Derived Mesenchymal Stem Cells From the Brain After Intra-arterial Infusion in Rats.

Intra-arterial (IA) delivery of bone marrow-derived mesenchymal stem cells (BM-MSCs) has shown potential as a minimally invasive therapeutic approach for stroke. The aim of the present study was to determine the whole-body biodistribution and clearance of technetium-99m ((99m)Tc)-labeled rat and human BM-MSCs after IA delivery in a rat model of transient middle cerebral artery occlusion (MCAO) using single-photon emission computed tomography (SPECT). Our hypothesis was that xenotransplantation has a major impact on the behavior of cells. Male RccHan:Wistar rats were subjected to sham operation or MCAO. Twenty-four hours after surgery, BM-MSCs (2 × 10(6) cells/animal) labeled with (99m)Tc were infused into the external carotid artery. Whole-body SPECT images were acquired 20 min, 3 h, and 6 h postinjection, after which rats were sacrificed, and organs were collected and weighed for measurement of radioactivity. The results showed that the majority of the cells were located in the brain and especially in the ipsilateral hemisphere immediately after cell infusion both in sham-operated and MCAO rats. This was followed by fast disappearance, particularly in the case of human cells. At the same time, the radioactivity signal increased in the spleen, kidney, and liver, the organs responsible for destroying cells. Further studies are needed to demonstrate whether differential cell behavior has any functional impact.

Technetium-99m-labeled nanofibrillar cellulose hydrogel for in vivo drug release.

Nanoscale celluloses have recently gained an increasing interest in modern medicine. In this study, we investigated the properties of plant derived nanofibrillar cellulose (NFC) as an injectable drug releasing hydrogel in vivo. We demonstrated a reliable and efficient method of technetium-99m-NFC labeling, which enables us to trace the in vivo localization of the hydrogel. The release and distribution of study compounds from the NFC hydrogel after subcutaneous injection in the pelvic region of BALB/c mice were examined with a multimodality imaging device SPECT/CT. The drug release profiles were simulated by 1-compartmental models of Phoenix® WinNonlin®. The NFC hydrogel remained intact at the injection site during the study. The study compounds are more concentrated at the injection site when administered with the NFC hydrogel compared with saline solutions. In addition, the NFC hydrogel reduced the elimination rate of a large compound, technetium-99m-labeled human serum albumin by 2 folds, but did not alter the release rate of a small compound (123)I-ß-CIT (a cocaine analogue). In conclusion, the NFC hydrogels is easily prepared and readily injected, and it has potential use as a matrix for controlled release or local delivery of large compounds. The interactions between NFC and specific therapeutic compounds are possible and should be investigated further.

Synthesis and biological evaluation of novel (123)I-labeled 4-(4-iodophenyl)butanoyl-L-prolyl-(2S)-pyrrolidines for imaging prolyl oligopeptidase in vivo.

Prolyl oligopeptidase (POP) may be associated with neuromodulation and development of neurodegenerative diseases and it was recently shown to participate in the inflammatory cascade along with matrix metalloproteinases. Radiotracers, which can be used for non-invasive imaging, are needed for investigating the role of POP in normal physiology and in pathophysiological conditions in vivo. We synthesized two novel POP-specific (123)I-radiolabeled 4-phenylbutanoyl-L-prolyl-pyrrolidines of which 4-(4-[(123)I]iodophenyl)butanoyl-L-prolyl-2(S)-cyanopyrrolidine ([(123)I]2f, Ki = 4.2 nM) was selected. The selected compound has an electrophilic cyano group that is known to increase the dissociation time of POP inhibitors. [(123)I]2f was synthesized in high radiochemical yield and purity (87 ± 4%, >99%, respectively) and with a specific activity of 456 ± 98 GBq/µmol. [(123)I]2f was evaluated in healthy mice (C57Bl/6JRccHsd) by ex vivo biodistribution studies and SPECT imaging. Pretreatment with the known inhibitor 4-phenylbutanoyl-L-prolyl-(2S)-cyanopyrrolidine (KYP-2047, 2d, Ki = 0.023 nM) showed that binding of [(123)I]2f was POP specific. In addition, [(123)I]2f was evaluated in models of neuroinflammation and acute localized inflammation. A minor increase in binding of [(123)I]2f was observed in the inflamed region in the acute localized inflammation model. Similar increase in binding was not observed in the neuroinflammation model.

Radiolabeled peptides for Alzheimer's diagnostic imaging: mini review.

The pathology of Alzheimer's disease (AD) is characterized by the extracellular and intracellular accumulation of amyloid-ß (Aß) fibrillar plaques formed by the Aß1-42 peptide, neurofibrillary tangles (NFTs) consisting of hyperphosphorylated tau, extensive neuritic and synaptic degradation, and neuron loss. One of the priorities for the treatment of AD is both the early detection and accurate chart progression of the accumulation of Aß plaques in human brains. Molecular imaging tools can provide an in vivo visualization of Aß plaques. Specific identification of amyloid plaques would allow a more accurate prognosis and ensure more effective clinical trials of anti-amyloid agents at earlier disease stage. The emphasis of this review is on the development of Aß peptide radiopharmaceuticals or the ones combined with nanocarrier-based such as Molecular Trojan horses or nanoparticles for applications in in vivo amyloid imaging in AD.

SPECT/CT imaging of radiolabeled cubosomes and hexosomes for potential theranostic applications.

We have developed a highly efficient method for the radiolabeling of phytantriol (PHYT)/oleic acid (OA)-based hexosomes based on the surface chelation of technetium-99m ((99m)Tc) to preformed hexosomes using the polyamine 1, 12-diamino-3, 6, 9-triazododecane (SpmTrien) as chelating agent. We also report on the unsuccessful labeling of cubosomes using the well-known chelating agent hexamethylpropyleneamine oxime (HMPAO). The (99m)Tc-labeled SpmTrien-hexosomes ((99m)Tc-SpmTrien-hexosomes) were synthesized with good radiolabeling (84%) and high radiochemical purity (>90%). The effect of radiolabeling on the internal nanostructure and the overall size of these aqueous dispersions was investigated by using synchrotron small angle X-ray scattering (SAXS), dynamic light scattering (DLS), and transmission electron cryo microscopy (cryo-TEM). Further, we show the utility of (99m)Tc-SpmTrien-hexosomes for the in vivo imaging of healthy mice using single photon emission computed tomography (SPECT) in combination with computed tomography (CT), i.e. SPECT/CT. SPECT/CT experiments of subcutaneously administered (99m)Tc-SpmTrien-hexosomes to the flank of mice showed a high stability in vivo allowing imaging of the distribution of the radiolabeled hexosomes for up to 24 h. These injected (99m)Tc-SpmTrien-hexosomes formed a deposit within the subcutaneous adipose tissue, displaying a high biodistribution of ≈ 343% injected dose/g tissue (%ID/g), with negligible uptake in other organs and tissues. The developed (99m)Tc labeling method for PHYT/OA-based hexosomes could further serve as a useful tool for investigating and imaging the in vivo performance of cubosomal and hexosomal drug nanocarriers.

Transient proteolytic modification of mesenchymal stromal cells increases lung clearance rate and targeting to injured tissue.

Systemic infusion of therapeutic cells would be the most practical and least invasive method of administration in many cellular therapies. One of the main obstacles especially in intravenous delivery of cells is a massive cell retention in the lungs, which impairs homing to the target tissue and may decrease the therapeutic outcome. In this study we showed that an alternative cell detachment of mesenchymal stromal/stem cells (MSCs) with pronase instead of trypsin significantly accelerated the lung clearance of the cells and, importantly, increased their targeting to an area of injury. Cell detachment with pronase transiently altered the MSC surface protein profile without compromising cell viability, multipotent cell characteristics, or immunomodulative and angiogenic potential. The transient modification of the cell surface protein profile was sufficient to produce effective changes in cell rolling behavior in vitro and, importantly, in the in vivo biodistribution of the cells in mouse, rat, and porcine models. In conclusion, pronase detachment could be used as a method to improve the MSC lung clearance and targeting in vivo. This may have a major impact on the bioavailability of MSCs in future therapeutic regimes.

High correlation between in vivo [123I]ß-CIT SPECT/CT imaging and post-mortem immunohistochemical findings in the evaluation of lesions induced by 6-OHDA in rats.

BACKGROUND: 6-Hydroxydopamine (6-OHDA) is widely used in pre-clinical animal studies to induce degeneration of midbrain dopamine neurons to create animal models of Parkinson's disease. The aim of our study was to evaluate the potential of combined single-photon emission computed tomography/computed tomography (SPECT/CT) for the detection of differences in 6-OHDA-induced partial lesions in a dose- and time-dependent manner using the dopamine transporter (DAT) ligand 2ß-carbomethoxy-3ß-(4-[123I]iodophenyl)tropane ([123I]ß-CIT). METHODS: Rats were unilaterally lesioned with intrastriatal injections of 8 or 2 × 10 µg 6-OHDA. At 2 or 4 weeks post-lesion, 40 to 50 MBq [123I]ß-CIT was administered intravenously and rats were imaged with small-animal SPECT/CT under isoflurane anesthesia. The striatum was delineated and mean striatal activity in the lesioned side was compared to the intact side. After the [123I]ß-CIT SPECT/CT scan, the rats were tested for amphetamine-induced rotation asymmetry, and their brains were immunohistochemically stained for DAT and tyrosine hydroxylase (TH). The fiber density of DAT- and TH-stained striata was estimated, and TH-immunoreactive cells in the rat substantia nigra pars compacta (SNpc) were stereologically counted. RESULTS: The striatal uptake of [123I]ß-CIT differed significantly between the lesion groups and the results were highly correlated to both striatal DAT- and TH-immunoreactive fiber densities and to TH-immunoreactive cell numbers in the rat SNpc. No clear progression of the lesion could be seen. CONCLUSIONS: [123I]ß-CIT SPECT/CT is a valuable tool in predicting the condition of the rat midbrain dopaminergic pathway in the unilateral partial 6-OHDA lesion model of Parkinson's disease and it offers many advantages, allowing repeated non-invasive analysis of living animals.

Rates of guideline adherence among US community oncologists treating NSCLC.

OBJECTIVES: To evaluate chemotherapy regimen utilization in patients with non-small cell lung cancer (NSCLC) treated in US community oncology practices, to examine the relationship between evidence-based guideline adherence and the follow-up monitoring period (FUMP) over 1.5 years, and to understand the relative costs of commonly administered chemotherapy regimens. STUDY DESIGN: Retrospective data analysis. METHODS: Using a large US medical oncology clinical database derived from a proprietary web-based drug dispensing technology, we identified adult patients with NSCLC who started adjuvant therapy for early-stage disease or first-line therapy for advanced and metastatic disease from July 1, 2009, through June 30, 2010. Adjuvant or first-line regimen utilization and the FUMP within 1.5 years were analyzed with respect to national evidence-based guideline adherence. Costs for commonly administered regimens based on 2010 Medicare reimbursement were compared. RESULTS: A total of 3505 patient treatment regimens were included in this study. Rates of guideline adherence were 75.0% and 61.3% for the first-line and the adjuvant treatment groups, respectively (P < .0001). Treatment with guidelinebased regimens correlated with a significantly longer FUMP in the first-line treatment groupcompared with non-guideline-based regimens (P = .005). Regimen costs for the top 11 regimens in the adjuvant and first-line treatment settings varied greatly. Low-cost regimens were prescribed more commonly. CONCLUSIONS: Rates of guideline adherence were significantly higher in the first-line than in the adjuvant NSCLC treatment group. First-line treatment with guideline-based regimens correlated with an extended FUMP for advanced NSCLC patients.

Advanced brain dopamine transporter imaging in mice using small-animal SPECT/CT.

BACKGROUND: Iodine-123-ß-CIT, a single-photon emission computed tomography (SPECT) ligand for dopamine transporters (DATs), has been used for in vivo studies in humans, monkeys, and rats but has not yet been used extensively in mice. To validate the imaging and analysis methods for preclinical DAT imaging, wild-type healthy mice were scanned using 123I-ß-CIT. METHODS: The pharmacokinetics and reliability of 123I-ß-CIT in mice (n = 8) were studied with a multipinhole SPECT/CT camera after intravenous injection of 123I-ß-CIT (38 ± 3 MBq). Kinetic imaging of three mice was continued for 7 h postinjection to obtain the time-activity curves in the striatum and cerebellum volumes. Five mice had repeated measures 4 h post-123I-ß-CIT injection to provide an indication of test-retest reliability. The same five mice served as a basis for a healthy mean SPECT template. RESULTS: Specific binding of 123I-ß-CIT within the mouse striatum could be clearly visualized with SPECT. The kinetics of 123I-ß-CIT was similar to that in previously published autoradiography studies. Binding potential mean values of the test-retest studies were 6.6 ± 15.7% and 6.6 ± 4.6%, respectively, and the variability was 9%. The SPECT template was aggregated from the first and second imaging of the test-retest animals. No significant difference between the templates (P > 0.05) was found. From the test template, a striatal volume of 22.3 mm3 was defined. CONCLUSIONS: This study demonstrates that high-resolution SPECT/CT is capable of accurate, repeatable, and semiquantitative measurement of 123I-ß-CIT DAT binding in the mouse brain. This methodology will enable further studies on DAT density and neuroprotective properties of drugs in mice.

Pre-targeting and direct immunotargeting of liposomal drug carriers to ovarian carcinoma.

BACKGROUND: Epidermal growth factor receptor (EGFR) is overexpressed in many solid tumor types, such as ovarian carcinoma. Immunoliposome based drug targeting has shown promising results in drug delivery to the tumors. However, the ratio of tumor-to-normal tissue concentrations should be increased to minimize the adverse effects of cytostatic drugs. METHODOLOGY/PRINCIPAL FINDINGS: We studied the EGFR-targeted doxorubicin immunoliposomes using pre-targeting and local intraperitoneal (i.p.) administration of the liposomes. This approach was used to increase drug delivery to tumors as compared to direct intravenous (i.v.) administration of liposomes. EGFR antibodies were attached on the surface of PEG coated liposomes using biotin-neutravidin binding. Receptor mediated cellular uptake and cytotoxic efficacy of EGFR-targeted liposomes were investigated in human ovarian adenocarcinoma (SKOV-3 and SKOV3.ip1) cells. In vivo distribution of the liposomes in mice was explored using direct and pre-targeting approaches and SPECT/CT imaging. Targeted liposomes showed efficient and specific receptor-mediated binding to ovarian carcinoma cells in vitro, but the difference in cytotoxicity between targeted and non-targeted liposomes remained small. The relatively low cytotoxic efficacy is probably due to insufficient doxorubicin release from the liposomes rather than lack of target binding. Tumor uptake of targeted liposomes in vivo was comparable to that of non-targeted liposomes after both direct and pre-targeting administration. For both EGFR-targeted and non-targeted liposomes, the i.p. administration increased liposome accumulation to the tumors compared to i.v. injections. CONCLUSIONS/SIGNIFICANCE: Intraperitoneal administration of liposomes may be a beneficial approach to treat the tumors in the abdominal cavity. The i.p. pre-targeting method warrants further studies as a potential approach in cancer therapy.

Microdosing, imaging biomarkers and SPECT: a multi-sided tripod to accelerate drug development.

The advances of nuclear medicine imaging instrumentation and radiopharmaceutical sciences allow their involvement in the developmental processes of therapeutic drugs. New chemical entities, meant as potential drugs, need to comply with the proof-of-principle. Tomographic imaging methods as PET, SPECT and CT have been used for small animal and human studies at an early stage of drug development. Using a drug candidate in a radiolabeled form in obtaining quantitative imaging data provides opportunity for a complete morphological and functional overview of targeting properties and overall pharmacokinetics. This can be helpful in go/no-go decision making. Microdosing, using e.g.1% of the proposed dose of the radiolabeled potential drug plays an important part in this early development and notably reduces the risk of serious adverse effects in human volunteers or patients. This paper primarily focuses on the way in which microdosing and SPECT imaging may contribute to the development of drugs. Furthermore, this paper illustrates how these techniques may help to eliminate weak drug candidates at early stage, making time and funds available for potential lead compounds. Eventually this approach facilitates and accelerates new drug approval. The present paper highlights how these techniques make drug development easier in the field of oncology and neurology.

Synthesis and biological evaluation of 6/7-exo-methyl-3beta-(4-iodo)phenyltropane-2beta-carboxylic acid methyl esters.

6beta/7beta-Methyl-2-methoxycarbonyltropinones (3a, 3b) were synthesized and used as starting materials in the synthesis of 6beta/7beta-methyl-2beta-methoxycarbonyl-3beta-phenyltropanes (6a, 6b), 6beta/7beta-methyl-2beta-methoxycarbonyl-3beta-(4-iodo)phenyltropanes (7a, 7b) and 6beta-methyl-2beta-methoxycarbonyl-3beta-(4-iodo)phenylnortropane (8). The effect of 6/7-groups was evaluated by in vitro receptor binding to dopamine (DAT), serotonin (SERT) and norepinephrine (NET) transporters. Introduction of a methyl group at the 6- or 7-position diminished the overall affinity for the transporters, though mostly to NET. In vivo locomotor tests were performed in mice for compounds 7a and 8. Compound 8 had no apparent effect on locomotor activity. Compound 7a increased locomotion in a wide dose range, but was much less potent than a reference compound, 2beta-carbomethoxy-3beta-(4-iodo)phenyl-tropane (beta-CIT).

Dopamine D2 receptors and transporters in type 1 and 2 alcoholics measured with human whole hemisphere autoradiography.

Increasing evidence implies the involvement of the dopamine (DA) system in the pathogenesis of alcoholism. We measured striatal DA D(2) receptors in Cloninger type 1 and 2 alcoholics by using [(125)I]epidepride in human postmortem whole hemispheric autoradiography (WHA), which provides high-resolution images corresponding to positron emission tomographic (PET) studies. We also evaluated the correlation between transporter and receptor DA binding site densities and putative correlation of [(125)I]epidepride binding between the dorsal striatum and nucleus accumbens. In the type 1 alcoholics, the DA D(2) receptor density was 21.4-32.6% lower in all dorsal striatal structures (caudate, putamen, globus pallidus) when compared with the controls. Type 2 alcoholics had 19.6-21.4% lower binding in other dorsal striatal structures, except medial globus pallidus, where they were not significantly different from controls. The density of DA D(2) receptors and DAT had a significant positive correlation only in the putamen of type 1 alcoholics. The binding of [(125)I]epidepride showed also consistent and statistically significant positive correlation between nucleus accumbens and all dorsal striatal areas in type 1 alcoholics but not in the controls. In the type 2 alcoholics, the correlation was weaker than that observed in the type 1 alcoholics, and no correlation was observed between nucleus accumbens and globus pallidus. Our results show that these two subgroups of alcoholics have stark differences in their DA D(2) receptor binding characteristics. Type 2 alcoholics may have selective deficiency in the dorsal striatum, whereas in limbic structures they may not differ significantly from controls. Moreover, WHA provides a useful tool for detailed mapping of neuronal receptors in healthy as well as diseased brain, and can also be used in radioligand development for PET.

Treatment improves serotonin transporter binding and reduces binge eating.

RATIONALE: Serotonin (5-HT) is involved in the control of eating behaviour by inhibiting food intake. Obese women with binge-eating disorder (OB-BED) were recently found to have reduced 5-HT transporter binding. OBJECTIVES: The aim of this study was to investigate the effect of a successful treatment on 5-HT transporters in OB-BED. METHODS: The 5-HT transporter binding of seven OB-BED was measured by single-photon emission computed tomography (SPECT), by using iodine-123-labelled nor-beta-CIT as a tracer, before treatment and after successful treatment, when the OB-BED were asymptomatic. Treatment consisted of group psychotherapy and fluoxetine medication. The control subjects, six obese women without eating disorders, were also studied twice by using SPECT. RESULTS: The 5-HT transporter binding of the symptomatically recovered OB-BED increased significantly (24+/-22%) after treatment, whereas in the control group, binding remained unchanged. CONCLUSIONS: The results tentatively suggest that 5-HT transporter binding in OB-BED is an adaptive mechanism, which can be affected by treatment. Furthermore, there seems to be a link between improved 5-HT transporter binding and reduced binge eating.

Different effect of age on dopamine transporters in the dorsal and ventral striatum of controls and alcoholics.

It is generally agreed that there is a deterioration in brain dopamine (DA) system with aging. The role of the mesolimbic DA in brain ethanol reinforcement is well established, with nucleus accumbens (NAC) serving as a major terminal area of this system, whereas dorsal striatum is more associated with motor control. The aim of this study was to compare putative age-related alterations of dopamine transporters (DAT) in dorsal and ventral striatum of healthy controls and alcoholics. We studied the effect of age on DAT in caudate (NC), putamen (Pu), and nucleus accumbens (NAC) of eight type 1 and 2 alcoholics and 10 healthy controls by using [(125)I]PE2I as a radioligand for postmortem human whole hemisphere autoradiography. In the type 1 alcoholic group age and DAT density did not correlate significantly with any of the structures studied. The mean densities of DAT declined significantly with age in controls and type 2 alcoholics in dorsal striatum (NC, Pu) (range of correlation coefficient from -0.49 to -0.94), but not statistically significantly in NAC. In type 1 alcoholics the lack of correlation between DAT density and age may indicate a preexisting dopaminergic deficit in this patient group, whereas age-related decline among type 2 alcoholics resembled that of healthy controls. Furthermore, dorsal striatal DAT may be more vulnerable to age-related decline than DAT in NAC. This is supported by the notion that DAT in NAC and dorsal striatum have different molecular weights.

Biodistribution and radiation dosimetry of [123I]ADAM in healthy human subjects: preliminary results.

[(123)I]ADAM [2-((2-((dimethylamino)methyl)phenyl)thio)-5-iodophenylamine (ADAM)] has recently been shown to be a very promising imaging ligand for the detection of serotonin transporters (SERT) in human brain, because of its high specificity for SERT. [(123)I]ADAM has previously been used only for animal studies. In this work, we investigated the radiation dosimetry and biodistribution of [(123)I]ADAM based on whole-body scans in healthy human volunteers. Following the administration of 196+/-20 MBq (range 157-220 MBq) [(123)I]ADAM, serial whole-body images were performed up to 24 h. Estimates of radiation absorbed dose were calculated using the MIRDOSE 3.0 program with a dynamic bladder model. Twelve source organs were considered in estimating absorbed radiation doses for organs of the body. The highest absorbed organ doses were found to the lower large intestine wall (8.3.10(-2) mGy/MBq), kidneys (5.2.10(-2) mGy/MBq), urinary bladder wall (4.9.10(-2) mGy/MBq) and thyroid (4.3.10(-2) mGy/MBq). The effective dose was estimated to be 2.2.10(-2) mSv/MBq. The results suggest that [(123)I]ADAM is of potential value as a tracer for single-photon emission tomography imaging of serotonin receptors in humans, with acceptable dosimetry and high brain uptake.

Serotonin transporter distribution and density in the cerebral cortex of alcoholic and nonalcoholic comparison subjects: a whole-hemisphere autoradiography study.

OBJECTIVE: Lesions of the medial prefrontal cortex and dysfunctions in serotonin turnover are two well-established factors associated with impulsive and sociopathic behaviors, but no firm neuroanatomical data have linked these pathophysiological findings. The aims of this study were to identify putative areas in the human brain that are rich in serotonin transporter sites, particularly within the medial prefrontal cortex, and to determine whether serotonin transporter density in this area is altered among alcoholic subjects. METHOD: Serotonin transporter density was measured among 17 alcoholic and 10 nonalcoholic comparison subjects by postmortem whole-hemisphere autoradiography with [(3)H]citalopram. RESULTS: In the human cerebral cortex, serotonin transporter binding sites were concentrated in the perigenual anterior cingulate cortex. Substantially sparser serotonin transporter density (up to 35%) was observed in the perigenual anterior cingulate cortex of alcoholic subjects in relation to nonalcoholic comparison subjects. After adjustment for age and postmortem delay, this finding remained statistically significant. CONCLUSIONS: A lower serotonin transporter density among the alcoholic subjects was observed, specifically in the so-called "affect" region, suggesting an association between ethanol addiction and dysfunctional serotonergic neurotransmission in this area.

Gender influence on vasoactive hormones at rest and during a 70 degrees head-up tilt in healthy humans.

To evaluate the influence of age and gender on the neuroendocrine control of blood pressure in normal subjects, a 13-min 70 degrees head-up tilt (HUT) was applied after 3 h of recumbency to 109 healthy men and women aged 23-50 yr (age group I) and 51-77 yr (age group II). We found that age and gender had a significant influence on plasma norepinephrine (PNE) concentration at baseline and in the upright position. PNE was significantly higher in older men compared with the younger men and women of both age groups, suggesting a divergent age-related activation of the sympathetic nervous system between genders at baseline as well as during a sustained orthostatic challenge. There was no significant influence of age or gender on plasma epinephrine at baseline or during HUT. Plasma renin activity was significantly higher at baseline as well as in the upright position during HUT in elderly men than in women. Age or gender had no influence on plasma vasopressin (PAVP), and, regardless of age, nonhypotensive HUT induced an extremely modest increase in PAVP. The syncopal subjects displayed a hormonal pattern associating increased PNE and a surge in plasma epinephrine and PAVP minutes before syncope during HUT. The orthostatic intolerance appears not to be a feature of healthy aging per se. In healthy subjects, both age and gender modulate markedly the cardiovascular and neuroendocrine responses to an orthostatic challenge and must be taken into consideration, particularly when catecholamine responses are studied.