Poor results of 5-aminolevulinic acid-photodynamic therapy for residual high-grade dysplasia and early cancer in barrett esophagus after endoscopic resection

BACKGROUND AND STUDY AIMS

The aim of the study was to evaluate the efficacy of photodynamic therapy (PDT) in the treatment of residual high-grade dysplasia or early cancer (HGD/EC) after endoscopic resection in Barrett esophagus.

PATIENTS AND METHODS

Study patients were separated into group A, with proven residual HGD/EC, and group B with possible HGD/EC (positive lateral margins in the endoscopic resection specimen, without HGD/EC in the remaining Barrett esophagus). PDT treatment consisted of 5-aminolevulinic (5-ALA) photosensitization (40 mg/kg) followed by illumination of the Barrett esophagus with a total light dose of 100 J/cm (2). Complete remission was defined as the absence of HGD/EC in biopsies taken in two consecutive follow-up endoscopies. The percentage regression of Barrett esophagus, as well as the recurrence rate of HGD/EC, was calculated.

RESULTS

20 patients underwent PDT (group A, 11; group B, 9). Mild complications were seen in 4/26 procedures. The overall success rate was 15/20 (75 %). There was a significant difference in success rate between group A (55 %) and group B (100 %); P = 0.03. All patients had residual Barrett esophagus after PDT; the median regression percentage was 50 % (IQR 25 - 70 %). Recurrence of HGD/EC occurred in four patients (two each in groups A and B) after a median follow up of 30 months.

CONCLUSIONS

In this selected group of patients, the addition of 5-ALA-PDT after endoscopic resection for HGD/EC had a disappointing success rate in patients who had residual HGD/EC after endoscopic resection. Most patients undergoing 5-ALA-PDT have residual Barrett mucosa after PDT and 5-ALA-PDT does not seem to prevent recurrences during follow-up.

Osteoblastic activity and neoangiogenesis in distracted bone of irradiated rabbit mandible with or without hyperbaric oxygen treatment

The effects of irradiation and hyperbaric oxygenation (HBO) on osteoblastic activity and angiogenesis in rabbit mandibular distraction (DO) were evaluated. Three groups were studied. The mandible of two groups received a 22.4Gy dose of irradiation. One of the irradiated groups was also given HBO, 18 times at 2.5ATA for 90min per day preoperatively. The third group was given neither radiotherapy nor HBO. Mandibular lengthening was performed unilaterally. Osteoblastic activity was assessed ex vivo by [18F]fluoride digital autoradiography. Neovascularization of distracted bone was evaluated histomorphometrically. Osteoblastic activity was higher in non-irradiated than irradiated animals. In non-irradiated rabbits, the activity was evenly distributed over the distraction area. In the irradiated groups, the activity was greater in the central third of the lengthened bone than the peripheral thirds. HBO changed the osteogenic pattern towards that of non-irradiated bone. In the non-irradiated group the number of blood vessels was 1.7-fold as compared to irradiated rabbits without HBO (P=0.0012), and the fewest number of vessels was found in irradiated rabbits without HBO. Blood vessels were more numerous in the central region than in peripheral regions in non-irradiated animals and irradiated animals with HBO, but not in irradiated rabbits without HBO therapy. It is concluded that radiotherapy disturbs distraction bone formation and neovascularization related to DO. HBO increases osteoblastic activity, but not to the level of non-irradiated bone. Angiogenic response is markedly increased by HBO.

Severe somatization in women is associated with altered cerebral glucose metabolism

BACKGROUND

Somatization is a clinical phenomenon characterized by multiple, medically unexplained somatic symptoms. The pathophysiology remains unknown. We aimed to test the hypothesis of a central nervous system dysfunction in the pathophysiology of this disorder.

METHOD

We studied 10 female patients diagnosed as having somatization disorder or undifferentiated somatoform disorder with no current Axis I disorders according to DSM-IV. They were compared with 17 healthy female volunteers using brain [18F]-fluorodeoxyglucose-PET with MRI reference.

RESULTS

The patients had lower cerebral metabolism rates of glucose (P<0.05) in both caudate nuclei, left putamen and right precentral gyrus compared with healthy volunteers.

CONCLUSIONS

This is the first study to demonstrate changes in brain metabolism in somatizing women. The regional cerebral hypometabolism is probably associated with the pathophysiology of somatization.

Sex differences in striatal presynaptic dopamine synthesis capacity in healthy subjects

BACKGROUND

There are sex differences in the clinical features of several neuropsychiatric illnesses associated with dopamine dysfunction. The effects of sex on brain dopaminergic function have been sparsely studied in human subjects using modern imaging techniques. We have previously reported that the apparent affinity of [(11)C]raclopride for striatal D(2) dopamine receptors in vivo is lower in women than in men, whereas D(2) receptor density is not different. This finding indirectly suggests that women have a higher synaptic concentration of dopamine in the striatum. We explored further the basis of this phenomenon in an independent study and hypothesized that striatal presynaptic dopamine synthesis capacity would also be elevated in women.

METHODS

A total of 23 healthy men and 12 healthy women (age range 20-60 years) were studied using positron emission tomography and [(18)F]fluorodopa.

RESULTS

Women had significantly higher striatal [(18)F]fluorodopa uptake (Ki values) than men. The difference was more marked in the caudate (+26%) than in the putamen (+12%). In addition, there was a negative correlation between striatal [(18)F]fluorodopa Ki values and age in men but not in women.

CONCLUSIONS

The results further substantiate sex differences in striatal dopaminergic function in humans. This finding may be associated with sex differences in vulnerability and clinical course of neuropsychiatric disorders with dopaminergic dysregulation, e.g., schizophrenia, alcohol dependence, and Parkinson's disease.

Caffeine: behavioral effects of withdrawal and related issues

Acquired tolerance to some behavioral effects of caffeine in humans is widely assumed to occur but is poorly documented and appears, at most, to be of low magnitude. Withdrawal from regular consumption of caffeine has been reported to result in a variety of symptoms, including: irritability, sleepiness, dysphoria, delerium, nausea, vomiting, rhinorrhea, nervousness, restlessness, anxiety, muscle tension, muscle pains and flushed face. Some of these same symptoms have been reported following excess intake of caffeine. The prevalence of symptoms reported on withdrawal in different studies also covers a wide range from 11% or less to 100%. It is suggested that the evidence leads to the conclusion that non pharmacological factors related to knowledge and expectation are the prime determinants of symptoms and their reported prevalence on withdrawal of caffeine after regular consumption.

Comparison of acute toxicities of indolo[3,2-b]carbazole (ICZ) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in TCDD-sensitive rats

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and related halogenated aromatic hydrocarbons are environmental toxicants that act via the AH receptor (AHR). In vitro studies have demonstrated that some indole derivatives present in cruciferous vegetables also bind to the AHR. One of the highest AHR binding affinities is exhibited by indolo[3,2-b]carbazole (ICZ). Since exposure to these dietary indoles is quantitatively far larger than that to halogenated aromatic compounds, their potential toxic risks have raised concern. In the present study, we compared the effects of ICZ with those of a single dose of 20 microg/kg TCDD in the most TCDD-sensitive rat strain (Long-Evans [Turku AB]) (L-E). Whereas TCDD elicited the expected toxicity syndrome, ICZ, either as a single subcutaneous dose (63.5, 127 or 508 microg/kg) or with repeated sc dosing (508 microg/kg for 5 days) failed to reproduce any toxic impacts of TCDD. Furthermore, a simultaneous ICZ treatment (63.5 or 127 microg/kg for 10 days) did not interfere with TCDD (20 microg/kg; single exposure) action. A moderate hepatic induction of CYP1A1 could be triggered by repeated intragastric administration of ICZ (127 microg/kg for 4 days, the last treatment 2.5 h prior to termination). In control experiments in a reconstituted yeast system, ICZ potently and dose-dependently activated L-E rat AHR function demonstrating that it represents a bona fide high-affinity ligand for the rat receptor in vivo. Thus, the present study does not support the view that dietary exposure to ICZ would present a hazard of AHR-mediated adverse health effects to humans.

Comparison of vedaprofen and meloxicam in dogs with musculoskeletal pain and inflammation

In this randomised, multicentre clinical study, dogs with musculoskeletal pain and inflammation were treated with either vedaprofen or meloxicam administered orally at the recommended dose rates. Clinical examinations were carried out regularly and clinical severity scores assigned. In total, 214 cases (73 acute, 141 chronic) were evaluated. Treatment with vedaprofen and meloxicam was continued for 14 and 17 days, respectively, in the acute cases, and 38 and 39 days in the chronic cases. NSAID treatment resulted in a significant improvement in clinical scores. The overall response to treatment ('responders') at the final clinical examination was 89 per cent and 87 per cent in the acute cases and 72 per cent and 65 per cent in the chronic cases in the vedaprofen and meloxicam groups, respectively. Mild transient gastrointestinal signs were observed in both groups (11 per cent vedaprofen, 12 per cent meloxicam). Adverse effects related to NSAIDs resulted in treatment cessation in 5 per cent of the dogs in each group. Vedaprofen and meloxicam were efficacious in, and well tolerated by, most of the dogs in the study.

2-[(18)F]fluoro-2-deoxy-D-glucose combined with microdialysis can be used for the comparison of tissue glucose metabolism in obese and lean rats

AIMS

Direct assessment of tissue metabolism in vivo is important to understand the pathogenesis of obesity. Labelled glucose analogues are potential candidates to be used for this purpose. The aim of this study was to compare the kinetics and metabolism of 2-[(18)F]fluoro-2-deoxy-D-glucose (FDG) in obese (fa/fa) and lean (Fa/?) Zucker rat tissues with microdialysis, and the measurement of uptake and phosphorylation with or without insulin bolus injection.

METHODS

Obese (n = 10) and lean (n = 11) anaesthetized rats underwent a microdialysis study after FDG-injection either with or without insulin stimulation. Microdialysis probes were inserted in the jugular vein, quadriceps muscle and liver. After 110 min, tissue [(18)F]-uptake and intracellular phosphorylation of FDG were studied in blood, liver, skeletal muscle, subcutaneous adipose tissue, intra-abdominal adipose tissue and hypothalamus.

RESULTS

When measured with microdialysis, insulin-enhanced FDG disappeared from the blood pool and interstitial space of skeletal muscle and liver more effectively in lean rather than in obese animals. Insulin-stimulated skeletal muscle and adipose tissue[(18)F]-uptake was impaired in obese Zucker rats compared with lean animals. Hypothalamic FDG uptake was six to sevenfold higher than in other measured tissues, but was attenuated in obese rats. In liver and in mesenteric fat, insulin-enhanced FDG phosphorylation in lean rats compared with obese animals.

CONCLUSIONS

Positron-emitting glucose analogue FDG, combined with microdialysis and tissue analysis, is a feasible method in studying glucose metabolism at the cellular level in animal studies.

Interactions between cocaine and dopamine agonists on cardiovascular function in squirrel monkeys

Conscious squirrel monkeys were treated i.v. with cocaine and various dopamine agonist drugs. Cocaine produced a dose-dependent increase in blood pressure, heart rate, and the rate-pressure product (RPP). The dopamine D1 receptor agonist (+/-)-6-chloro-3-allyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrobromide (SKF 82958) produced effects comparable to cocaine. The D1 agonist (+/-)-6-chloro-7, 8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrobromide (SKF 81297) also produced increases in blood pressure and heart rate but was much less potent than either cocaine or SKF 82958. The partial D1 agonist (+/-)-7,8-dihydroxy-3-allyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SKF 77434) did not significantly affect any cardiovascular parameters. The D2 agonist quinpirole slightly decreased blood pressure and increased heart rate. As such, the RPP only slightly increased. The selective dopamine uptake inhibitor 1-[2-[bis-(4-fluorphenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine (GBR 12909) produced increases in blood pressure, heart rate, and RPP, but again these effects were smaller and only seen at doses higher than cocaine. Effects similar to those with GBR 12909 were seen with the dopamine autoreceptor antagonist cis-(+)-5-methoxy-1-methyl-2-(di-n-propylamino)tetralin (UH 232). The combination of GBR 12909, SKF 82958, or SKF 77434 with cocaine produced effects that were clearly subadditive. The effects of quinpirole in combination with cocaine were comparable to, or lower than, those of cocaine alone on blood pressure and RPP. The effects on heart rate were additive. Only UH 232 produced additive effects with cocaine for all three measures. As dopamine agonists have been proposed as potential treatments for cocaine abuse, these results suggest that dopamine D1 agonists and uptake inhibitors can be used safely in combination with cocaine. Caution may be warranted, however, with the use of dopamine autoreceptor antagonists in the treatment of cocaine abuse.

Tacrolimus clinical studies for atopic dermatitis and other conditions

The first topical immunomodulator approved for human use, tacrolimus ointment (Protopic, Fujisawa, Healthcare, Inc, Deerfield, IL), has been shown to be effective and safe in the treatment of children (aged 2 years and older) and adults with atopic dermatitis (AD). Clinical trials conducted worldwide have involved 12,000 patients, with safety and efficacy data available for up to 3 years of treatment. In addition to its beneficial effects in the management of AD, topical tacrolimus has also been reported to be of benefit in other immunologically mediated skin diseases including: hand dermatitis, contact dermatitis, eyelid dermatitis, erosive lichen planus, steroid-induced rosacea, pyoderma gangrenosum, and graft-versus-host disease. This article reviews the clinical experience of topical tacrolimus in the treatment of AD and other skin conditions.

Psychomotor stimulant effects of beta-phenylethylamine in monkeys treated with MAO-B inhibitors

RATIONALE AND OBJECTIVE

Sufficiently high doses of beta-phenylethylamine (beta-PEA), a trace amine that is rapidly metabolized by monoamine oxidase-type B (MAO-B), can produce effects comparable to those of cocaine or methamphetamine (MA). The present experiments were conducted to study how the discriminative-stimulus (S(D)) and reinforcing-stimulus (S(R)) effects of beta-PEA in monkeys are modified by treatment with inhibitors of MAO-B [R-(-)-deprenyl and MDL 72974].

METHODS AND RESULTS

In studies of its S(D) effects, doses of beta-PEA up to 30 mg/kg engendered only sporadic responding on the drug-associated lever in squirrel monkeys that discriminated intramuscular injections of 0.3 mg/kg MA from vehicle whereas lower doses of 0.3-1.0 mg/kg beta-PEA produced full substitution when administered after either R-(-)-deprenyl or MDL 72974 (0.3 mg/kg). The MA-like S(D) effects of beta-PEA were attenuated by either dopamine D(1) or D(2) receptor blockers. In studies of its S(R) effects, high doses of beta-PEA maintained responding in two of three monkeys under a second-order fixed-interval schedule (3.0 or 10 mg/kg per injection) and two of three monkeys under a simple fixed ratio (FR) schedule (0.3-1.0 mg/kg per injection) of intravenous (i.v.) self-administration. MAO-B inhibition by R-(-)-deprenyl or MDL 72974 enhanced the S(R) effects of beta-PEA in all monkeys and, under the FR schedule, induced a 30-fold or greater leftward shift in the dose-response function for its i.v. self-administration. Based on time-course determinations, the enhanced S(R) effects of beta-PEA under the FR schedule were long-lasting and dissipated gradually over 3-7 days.

CONCLUSIONS

These results show that inhibition of MAO-B enhances S(D) and S(R) effects of beta-PEA in monkeys, presumably by delaying its inactivation. MAO-B inhibition leading to increased levels of beta-PEA may be useful, alone or in combination with other therapeutic agents, in the pharmacological management of selected aspects of drug dependence.

Personality traits and brain dopaminergic function in Parkinson's disease

A distinctive personality type, characterized by introversion, inflexibility, and low novelty seeking, has been suggested to be associated with Parkinson's disease. To test the hypothesis that Parkinson's disease is associated with a specific dopamine-related personality type, the personality structures of 61 unmedicated Parkinson's disease patients and 45 healthy controls were examined. Additionally, in 47 Parkinson's disease patients, the dopaminergic function in the brain was directly measured with 6-[(18)F]fluoro-l-dopa ((18)F-dopa) positron emission tomography (PET) with MRI coregistration. The novelty-seeking personality score, supposedly associated with the parkinsonian personality, was slightly lower in the Parkinson's disease group compared with controls, but it did not have a significant relationship with (18)F-dopa uptake in any of the brain regions studied (r = -0.12 to 0.11, P > 0.15). The harm-avoidance personality score, associated with anxiety and depression, was clearly increased in patients with Parkinson's disease and it had a paradoxical, highly significant positive correlation with the (18)F-dopa uptake in the right caudate nucleus (r = 0.53, P = 0.04, Bonferroni corrected for 220 comparisons). Although the results of this study are not in disagreement with the concept of low-novelty-seeking personality type in Parkinson's disease, the personality type does not seem to be dopamine dependent. The correlation between the personality trait of harm avoidance and (18)F-dopa may reflect a specific feedback circuitry of neurotransmitters that is associated with negative emotionality in Parkinson's disease.

Imaging of blood flow and hypoxia in head and neck cancer: initial evaluation with [(15)O]H(2)O and [(18)F]fluoroerythronitroimidazole PET

Hypoxia is a characteristic feature of malignant tumors that should be evaluated before the start of therapy. (18)F-labeled fluoroerythronitroimidazole (FETNIM) is a possible candidate for imaging tumor hypoxia with PET. Quantitative analysis of [(18)F]FETNIM uptake in vivo is necessary before proceeding to assays predicting hypoxia.

METHODS

Eight patients with untreated head and neck squamous cell carcinoma were enrolled in the study. All patients underwent dynamic PET imaging with [(18)F]FETNIM, coupled with measurements of blood flow with [(15)O]H(2)O and blood volume with [(15)O]CO. The metabolically active tumor volume was determined from [(18)F]FDG PET performed on a separate day. [(18)F]FETNIM uptake in the tumor was correlated with that in neck muscles and arterial plasma and compared with the findings of other PET studies.

RESULTS

Blood flow in tumor was 5- to 30-fold greater than in muscle, in contrast to blood volume, which did not significantly differ in the 2 tissues. With [(18)F]FETNIM PET, muscle activity remained invariably less than plasma activity, whereas activity in whole tumors was always greater than that in muscle. In 4 instances, the maximum tumor uptake of [(18)F]FETNIM was 1.2-2.0 times higher than plasma activity in the late dynamic phase. A kinetic model developed for calculation of distribution volume of reversibly trapping tracers was successfully applied in the [(18)F]FETNIM studies. Tumor distribution volume correlated strongly with the standardized uptake value of [(18)F]FETNIM between 60 and 120 min and with blood flow but not with the standardized uptake value of [(18)F]FDG. The relationship between [(18)F]FETNIM uptake and the blood flow of the tumor was less obvious on a pixel-by-pixel level.

CONCLUSION

Uptake of [(18)F]FETNIM in head and neck cancer is highly variable and seems to be governed by blood flow at least in the early phase of tissue accumulation. Maximum tumor-to-muscle tracer uptake ratios > 180 min were in the range of 1-4, comparing favorably with those reported previously for [(18)F]fluoromisonidazole. Assessment of the distribution volume of [(18)F]FETNIM after the initial blood-flow phase is feasible for subsequent evaluation of hypoxia-specific retention.

Decreased striatal dopamine transporter binding in vivo in chronic schizophrenia

We have previously reported that average striatal dopamine transporter (DAT) binding in vivo is unaltered in neuroleptic-naive first-episode schizophrenic patients [Laakso et al., Am. J. Psychiatry 157 (2000) 269]. However, as it has been suggested that some of the brain changes in schizophrenia may vary depending on the illness phase, we studied DAT density in eight stable, medicated chronic schizophrenic patients and eight matched controls using positron emission tomography and [18F]CFT, a marker of dopamine nerve terminals. [18F]CFT binding potentials were significantly lower in chronic schizophrenic patients than in controls, both in the caudate and the putamen (-9 to -16%). Together with the finding of unchanged average striatal DAT levels in first-episode patients and relative insensitivity of striatal [18F]CFT binding to endogenous dopamine and neuroleptic drugs, the result is in line with a relative loss of striatal dopaminergic nerve terminals and/or decreased expression of DAT in a subset of chronic schizophrenic patients.

Synthesis of S-([18F]fluoromethyl)-(+)-McN5652 as a potential PET radioligand for the serotonin transporter

The present study describes the synthesis of the [18F]fluoromethyl analogue of (+)-McN5652 ([18F]FMe-McN) as a new potential tracer for the serotonin transporter. In vitro binding studies have shown that FMe-McN displays only slightly lower affinity for the serotonin transporter (K(i) = 2.3 +/- 0.1 nM) than (+)-McN5652 (K(i) = 0.72 +/- 0.2 nM). The radiofluorinated tracer [18F]FMe-McN was prepared by reaction of normethyl (+)-McN5652 with the fluoromethylation agent [18F]bromofluoromethane in an overall radiochemical yield of 5 +/- 1% (decay-corrected, related to [18F]fluoride) and with high specific radioactivity (200-2,000 GBq/micromol at the end of synthesis).

Positron emission tomography shows that impaired frontal lobe functioning in Parkinson's disease is related to dopaminergic hypofunction in the caudate nucleus

We examined the relation between the dopaminergic function and the cognitive performance of patients with Parkinson's disease (PD). The subject sample consisted of ten patients in the early course of PD and with no previous antiparkinsonian medication. The dopaminergic function of the caudate nucleus and the putamen was studied with [(18)F]fluorodopa positron emission tomography, and the cognitive performance with a comprehensive battery of neuropsychological tests including tests sensitive to frontal lobe function. The decreased [(18)F]fluorodopa uptake in the right caudate nucleus was found to be related to slow processing time, measured as the difference between the incongruent and the congruent subtests of the Stroop Test (r=-0.85, P=0.002), a similar trend was seen in the left caudate (r=-0.60, P=0.07). Similar correlation was not detected in the putamen. The present findings provide evidence that the decreased dopaminergic function in the right caudate nucleus is related to the impaired performance in tests sensitive to frontal lobe function in patients at an early stage of PD and with no antiparkinsonian medication.

Pharmacokinetics of [18F]FETNIM: a potential marker for PET

18F-labeled fluoroerythronitroimidazole (FETNIM) has been suggested as a marker of tumor hypoxia for use with PET. Our goal was to evaluate the pharmacokinetic properties of [18F]FETNIM in rats and analyze metabolites in human, dog, and rat plasma and urine. Metabolites in liver and tumor homogenates from tumor-bearing rats, as well as the biodistribution of the tracer, were also studied.

METHODS

Radio-thin-layer chromatography and digital autoradiography were used to distinguish metabolites from the parent drug in urine and plasma from 8 patients, 3 dogs, and 18 rats, as well as in liver and tumor homogenates from Sprague-Dawley rats bearing 7,12-dimethylbenzanthracene-induced rat mammary carcinoma. Biodistribution of [18F]FETNIM was also studied in rats at 15, 30, 60, 120, and 240 min after tracer injection.

RESULTS

Most of the radioactivity in plasma and urine was the unchanged tracer, whereas rat liver homogenates contained almost only metabolites of [18F]FETNIM. None of the species studied showed binding of tracer to plasma proteins. A large variation-3%-70%-in the radioactivity represented by unchanged [18F]FETNIM was found in rat tumor. A negative correlation was found between the percentage of radioactivity represented by unchanged [18F]FETNIM in tumor tissue and tumor uptake (percentage injected dose per gram of tissue) at later times. The highest radioactivity was seen in urine and kidney; the lowest uptake was in fat, cerebellum, and bone matrix. In contrast to matrix, bone marrow had high uptake of 18F. The tumor-to-blood ratio reached a maximum of 1.80 +/- 0.64 at 2 h.

CONCLUSION

We conclude that [18F]FETNIM shows low peripheral metabolism, little defluorination, and possible metabolic trapping in hypoxic tumor tissue. These suggest a potential use for this tracer in PET studies on hypoxia of cancer patients.

Different types of GABA(A) receptors may mediate the anticonflict and response rate-decreasing effects of zaleplon, zolpidem, and midazolam in squirrel monkeys

RATIONALE

The role of different types of GABA(A) receptors in mediating anticonflict and response rate-decreasing effects of benzodiazepines in primate species is not known.

OBJECTIVE

To examine the behavioral effects of the benzodiazepine-site, GABA(A) agonists zolpidem, zaleplon, and midazolam in the presence of two antagonists, flumazenil and beta-carboline-3-carboxylate-t-butyl ester (beta-CCt) in squirrel monkeys.

METHODS

Two schedules of operant responding were used: (1) a multiple fixed-ratio (FR) schedule of food presentation involving punished and nonpunished behavior, and (2) an FR schedule of stimulus shock-termination.

RESULTS

Midazolam (0.03-1.0 mg/kg), zolpidem (0.1-3.0 mg/kg), and zaleplon (0.1-3.0 mg/kg) increased rates of punished responding and decreased rates of nonpunished responding under the multiple schedule. Pretreatment with flumazenil (0.3-1.0 mg/kg) antagonized the anticonflict and response rate-decreasing effects of all three agonists. Pretreatment with beta-CCt (3-10 mg/kg) antagonized the anticonflict and rate-decreasing effects of midazolam, as well as the rate-decreasing effects of zolpidem and zaleplon. However, beta-CCt did not antagonize the anticonflict effects of zolpidem and zaleplon; instead, these effects of zolpidem and zaleplon were apparently enhanced in the presence of beta-CCt. Under the schedule of stimulus shock-termination, both flumazenil and beta-CCt antagonized zolpidem and zaleplon; however, the effects of beta-CCt were less consistent than the effects of flumazenil.

CONCLUSION

In nonhuman primates, different types of GABAA receptors may mediate the anticonflict and the response rate-decreasing effects of the nonselective GABAA agonist midazolam and the selective GABAA1 agonists zolpidem and zaleplon.

Increased frontal [(18)F]fluorodopa uptake in early Parkinson's disease: sex differences in the prefrontal cortex

Previous imaging studies in Parkinson's disease have focused mainly on the striatum, a region with very high dopaminergic activity. Using modern high-sensitivity 3D [(18)F]fluorodopa (Fdopa)-PET, mesocortical monoamine projections can be studied. To study the frontal monoaminergic system in unmedicated early Parkinson's disease in vivo, we examined 20 early Parkinson's disease patients (10 women, 10 men) and 16 healthy subjects (nine women, seven men) with 3D Fdopa-PET, using standard region-of-interest-based analysis with MRI co-registration. Women with Parkinson's disease had 87% higher Fdopa uptake in the right dorsolateral prefrontal cortex (area 46) compared with men with Parkinson's disease, whereas there was no sex difference in the control group (sex x disease interaction, P = 0.03). The uptake in the right dorsolateral prefrontal cortex was 82% higher in men with Parkinson's disease and 219% higher in women with Parkinson's disease compared with control groups (effect of disease, P < 0.0001). Also in the left dorsolateral prefrontal cortex and in the medial frontal cortex, early Parkinson's disease patients had significantly (18-94%) higher Fdopa uptake compared with healthy controls. In the putamen, both men and women with Parkinson's disease had a significantly lower (27-46%) uptake compared with healthy controls. These results indicate that frontal monoaminergic activity is increased and that there is a sex difference in the prefrontal monoaminergic system in early Parkinson's disease. The reported sex difference may be linked to clinical sex differences in the symptoms and treatment response in Parkinson's disease.