Optical Activation of TrkB (E281A) in Excitatory and Inhibitory Neurons of the Mouse Visual Cortex

The activation of tropomyosin receptor kinase B (TrkB), the receptor of brain-derived neurotrophic factor (BDNF), plays a key role in induced juvenile-like plasticity (iPlasticity), which allows restructuring of neural networks in adulthood. Optically activatable TrkB (optoTrkB) can temporarily and spatially evoke iPlasticity, and recently, optoTrkB (E281A) was developed as a variant that is highly sensitive to light stimulation while having lower basal activity compared to the original optoTrkB. In this study, we validate optoTrkB (E281A) activated in alpha calcium/calmodulin-dependent protein kinase type II positive (CKII⁺) pyramidal neurons or parvalbumin-positive (PV⁺) interneurons in the mouse visual cortex by immunohistochemistry. OptoTrkB (E281A) was activated in PV⁺ interneurons and CKII⁺ pyramidal neurons with blue light (488 nm) through the intact skull and fur, and through a transparent skull, respectively. LED light stimulation significantly increased the intensity of phosphorylated ERK and CREB even through intact skull and fur. These findings indicate that the highly sensitive optoTrkB (E281A) can be used in iPlasticity studies of both inhibitory and excitatory neurons, with flexible stimulation protocols in behavioural studies.

Pharmacological and optical activation of TrkB in Parvalbumin interneurons regulate intrinsic states to orchestrate cortical plasticity

Elevated states of brain plasticity typical for critical periods of early postnatal life can be reinstated in the adult brain through interventions, such as antidepressant treatment and environmental enrichment, and induced plasticity may be critical for the antidepressant action. Parvalbumin-positive (PV) interneurons regulate the closure of developmental critical periods and can alternate between high and low plasticity states in response to experience in adulthood. We now show that PV plasticity states and cortical networks are regulated through the activation of TrkB neurotrophin receptors. Visual cortical plasticity induced by fluoxetine, a widely prescribed selective serotonin reuptake inhibitor (SSRI) antidepressant, was lost in mice with reduced expression of TrkB in PV interneurons. Conversely, optogenetic gain-of-function studies revealed that activation of an optically activatable TrkB (optoTrkB) specifically in PV interneurons switches adult cortical networks into a state of elevated plasticity within minutes by decreasing the intrinsic excitability of PV interneurons, recapitulating the effects of fluoxetine. TrkB activation shifted cortical networks towards a low PV configuration, promoting oscillatory synchrony, increased excitatory-inhibitory balance, and ocular dominance plasticity. OptoTrkB activation promotes the phosphorylation of Kv3.1 channels and reduces the expression of Kv3.2 mRNA providing a mechanism for the lower excitability. In addition, decreased expression and puncta of Synaptotagmin2 (Syt2), a presynaptic marker of PV interneurons involved in Ca²⁺-dependent neurotransmitter release, suggests lower inputs onto pyramidal neurons suppressing feed-forward inhibition. Together, the results provide mechanistic insights into how TrkB activation in PV interneurons orchestrates the activity of cortical networks and mediating antidepressant responses in the adult brain.

White matter lesions and brain atrophy in systemic lupus erythematosus patients: correlation to cognitive dysfunction in a cohort of systemic lupus erythematosus patients using different definition models for neuropsychiatric systemic lupus erythematosus

Aim

The aim of this study was to evaluate the extent of white matter lesions, atrophy of the hippocampus and corpus callosum, and their correlation with cognitive dysfunction (CD), in patients diagnosed with systemic lupus erythematosus (SLE).

Methods

Seventy SLE patients and 25 healthy individuals (HIs) were included in the study. To evaluate the different SLE and neuropsychiatric SLE (NPSLE) definition schemes, patients were grouped both according to the American College of Rheumatology (ACR) definition, as well as the more stringent ACR-Systemic Lupus International Collaborating Clinics definition. Patients and HIs underwent a 3 Tesla brain MRI and a standardized neuropsychological test. MRI data were evaluated for number and volume of white matter lesions and atrophy of the hippocampus and corpus callosum. Differences between groups and subgroups were evaluated for significance. Number and volume of white matter lesions and atrophy of the hippocampus and corpus callosum were correlated to cognitive dysfunction.

Results

The total volume of white matter lesions was significantly larger in SLE patients compared to HIs ( p = 0.004). However, no significant differences were seen between the different SLE subgroups. Atrophy of the bilateral hippocampus was significantly more pronounced in patients with NPSLE compared to those with non-NPSLE (right: p = 0.010; left p = 0.023). Significant negative correlations between cognitive test scores on verbal memory and number and volume of white matter lesions were present.

Conclusion

SLE patients have a significantly larger volume of white matter lesions on MRI compared to HIs and the degree of white matter lesion volume correlates to cognitive dysfunction, specifically to verbal memory. No significant differences in the number or volume of white matter lesions were identified between subgroups of SLE patients regardless of the definition model used.

Randomized assessment of imatinib in patients with acute ischaemic stroke treated with intravenous thrombolysis

BACKGROUND

Imatinib, a tyrosine kinase inhibitor, has been shown to restore blood-brain barrier integrity and reduce infarct size, haemorrhagic transformation and cerebral oedema in stroke models treated with tissue plasminogen activator. We evaluated the safety of imatinib, based on clinical and neuroradiological data, and its potential influence on neurological and functional outcomes.

METHODS

A phase II randomized trial was performed in patients with acute ischaemic stroke treated with intravenous thrombolysis. A total of 60 patients were randomly assigned to four groups [3 (active): 1 (control)]; the active treatment groups received oral imatinib for 6 days at three dose levels (400, 600 and 800 mg). Primary outcome was any adverse event; secondary outcomes were haemorrhagic transformation, cerebral oedema, neurological severity on the National Institutes of Health Stroke Scale (NIHSS) at 7 days and at 3 months and functional outcomes on the modified Rankin scale (mRS).

RESULTS

Four serious adverse events were reported, which resulted in three deaths (one in the control group and two in the 400-mg dose group; one patient in the latter group did not receive active treatment and the other received two doses). Nonserious adverse events were mostly mild, resulting in full recovery. Imatinib ameliorated neurological outcomes with an improvement of 0.6 NIHSS points per 100 mg imatinib (P = 0.02). For the 800-mg group, the mean unadjusted and adjusted NIHSS improvements were 4 (P = 0.037) and 5 points (P = 0.012), respectively, versus controls. Functional independence (mRS 0-2) increased by 18% versus controls (61 vs. 79; P = 0.296).

CONCLUSION

This phase II study showed that imatinib is safe and tolerable and may reduce neurological disability in patients treated with intravenous thrombolysis after ischaemic stroke. A confirmatory randomized trial is currently underway.

Positron Emission Tomography and Computed Tomography in Differential Diagnosis between Recurrent or Residual Glioma and Treatment-Induced Brain Lesions

In previous studies of supratentorial gliomas with positron emission tomography (PET) and computed tomography (CT), high uptakes of L-methyl-11C-methionine (11C-L-methionine) were found even in astrocytomas without blood-brain barrier defects as judged by CT or 68Ga-EDTA PET. In a number of patients examined after radiation therapy, there were no consistent changes in the high uptake values. In the present investigation PET and CT were compared with regard to their abilities to visualize and delineate recurrent tumors and treatment-induced brain defects and to differentiate between them. The study was undertaken on four patients who were long-term survivors after treatment for high-grade gliomas. For PET, 11C-L-methionine and 68Ga-EDTA were used. In two patients recurrent/residual tumors appeared considerably larger with 11C-L-methionine PET than with CT or 68Ga-EDTA PET. In one patient, no signs of recurrence were seen with any of these three methods, and in a fourth patient, whose condition was clinically stable, the findings at PET with 11C-L-methionine were non-specific. In areas corresponding to the surgical parenchymal defects, the 11C-L-methionine uptake and, except in one case, the local blood volume was markedly reduced. PET with 11C-L-methionine thus has a potential for distinguishing between postoperative brain lesions and tumor recurrence with a higher accuracy than CT.

MR Imaging in Cerebral Gliomas

A comparative analysis between MR examinations and histopathologic whole-brain sections regarding tumour components was performed in 5 brain specimens from patients with malignant glial brain tumours. All cases were examined with MR imaging in vitro and in 2 cases a close comparison with the MR examinations in vivo was also possible. The most homogeneous hypercellular area in malignant gliomas, giving the highest tumour grade, was not visualised on MR imaging as an isolated entity, either in vitro or in vivo. The most conspicuous tumour component, reflecting the heterogeneity of malignant gliomas, was necrosis. This feature was best depicted in the T2WI. In 4 of 5 cases, distant tumour spread of benign-looking tumour cells was found in areas visualised as normal on T2WI, outside the margins of the peritumoural oedema. In 2 cases, estimation of water content was performed immunohistochemically and a close correlation was found in each case between peritumoural and periventricular hyperintensity on T2WI and areas of pallor on the haematoxylin-eosin-stained whole-brain sections. These areas corresponded to microscopical oedema. MR imaging reflects underlying heterogeneous histopathology in malignant gliomas. The degree of malignancy of the lesion as a whole can thus be assessed by MR imaging. However, the method does not allow malignant gliomas to be correctly delineated.

Comparison of the Accumulation Kinetics of L-(Methyl-11C)-Methionine and D-(Methyl-11C)-Methionine in Brain Tumors Studied with Positron Emission Tomography

Five patients with glioma were examined with positron emission tomography after the administration of 11C-L-methionine and at a following day with 11C-D-methionine. The rates of accumulation of the tracers were determined in the tumor and in the normal brain tissue according to a graphical technique of Patlak et coll. (24). The accumulation rates for L-methionine were on the average 2.4 times higher than those of D-methionine in the tumors. The corresponding ratio for normal brain tissue was 2.3. It is concluded that in this group of tumors without obvious blood-tumor-barrier breakdown, a stereospecific process with similar properties as in the normal brain tissue, is responsible for the accumulation of the labelled methionine.

Delineation of Gliomas with Magnetic Resonance Imaging Using Gd-DTPA in Comparison with Computed Tomography and Positron Emission Tomography

Fourteen patients with cerebral gliomas were investigated by MR imaging using Gd-DTPA (Magnevist), CT with the contrast agent iohexol (Omnipaque) and, as a reference, positron emission tomography (PET) using 11C-L-methionine. Tumour areas with disruption of the blood-brain-barrier (BBB) as seen on MR and CT were compared with areas with increased accumulation of methionine in PET. There were 6 patients with high-grade astrocytoma (grade III-IV), 5 with low-grade astrocytoma (grade I–II) and 3 with oligodendroglioma. In 4 high-grade tumours, PET showed a larger tumour or tumour tissue in additional areas, compared with enhancement on MR and CT, while in 2 cases the tumour extension was similar in the three modalities. In the low grade tumour group, the findings on PET differed from those on post-contrast MR or CT in 7 cases. In 3 of these cases, no disruption of the BBB was seen either on MR or on CT. In 2 of our 14 patients CT showed larger enhancement extension than MR and in 2 cases MR was superior to CT in this respect. The enhancement intensity was higher on MR in 4 patients and on CT in 2 patients. No definite difference in the delineation of tumour tissue between the T1 weighted SE sequences used was found. The gradient echo sequences FLASH and FISP gave limited information that was less than that provided by the T1 weighted SE sequences. A greater increase in signal intensity in T1 weighted images was usually seen 5 min post-contrast in the high-grade tumours than in the low-grade ones.

Intracranial vessel wall MRI

There are many different methods of imaging the intracranial arteries; however, the vast majority of currently used techniques are based on luminal imaging. Although this is useful, it does have limitations as many different pathological processes can produce the same appearance. Therefore, directly imaging the site of the pathology - the vessel wall itself - offers the hope of discriminating between different disease processes. In this review, we will discuss the current status of vessel wall magnetic resonance imaging alongside its potential usefulness in differentiating between various disease entities.

First Report of Phytophthora ramorum and P. inflata in Ornamental Rhododendrons in Finland

Phytophthora ramorum was found for the first time in Finland during the spring of 2004 on marketed plants of Rhododendron spp. originating in other EU member states. During August of 2004, the pathogen was also found in one Finnish nursery on German Rhododendron catawbiense plants and several Finnish Rhododendron spp. cultivars. P. ramorum was detected by species-specific PCR and isolated (1). It was first characterized by an abundant production of chlamydospores on PARP and V8 agar, absence of oogonia and antheridia, and elongate, ellipsoid, deciduous, semipapillate sporangia produced in soil extract water (3). A partial sequence of the β-tubulin gene was identical to that of P. ramorum deposited in GenBank. Despite strict regulations governing the movement of plants, the pathogen has been found every year since 2004 on materials transported to Finland from other EU countries. A total of 586 samples were taken from symptomatic plants of several susceptible species from 2004 to 2006. P. ramorum was detected in 51 rhododendron samples and the number of the outbreak sites was 28. In domestic plant production, P. ramorum was found in only one nursery. The infected plants in this nursery were destroyed in 2005 according to the EU regulation 2004/426/EG. During the 2006 growing season, 84 samples from trace-forward inspections and reinspections of the nursery were tested and P. ramorum was not detected in any of the samples. In 2005, surveys for P. ramorum on Finnish Rhododendron spp. cultivars with necrotic lesions on leaves and blackened tips yielded, in addition to P. ramorum, another Phytophthora sp. On V8 agar, this homothallic species showed a stellate growth pattern with sparse aerial mycelium. Oogonia had both paragynous and amphigynous antheridia, and sporangia produced in soil extract water were ellipsoid in shape and semipapillate. A 763-bp segment of the β-tubulin gene was sequenced and was identical to the β-tubulin sequence of P. inflata strain IMI342898 (GenBank), which was isolated in 1990 from Syringa sp. in the UK. It is likely that this P. inflata strain has been spreading in Europe with the ornamental plant trade. To fulfill Koch's postulates, rhododenrdon plants were inoculated (2) with P. inflata or P. ramorum, typical symptoms observed, and the pathogens were reisolated from inoculated plants. Both Phytophthora species also caused necrotic lesions on Alnus glutinosa, A. incana, and Betula pendula. Pinus sylvestris was resistant to both Phytophthora spp., whereas Picea abies was susceptible to P. inflata but not P. ramorum. References: (1) EPPO Bull. 36:145, 2006. (2) E. Hansen et al. Plant Dis. 89:63, 2005. (3) S. Werres et al. Mycol. Res. 105:1155, 2001.

Differential protease, innate immunity, and NF-kappaB induction profiles during lung inflammation induced by subchronic cigarette smoke exposure in mice

Cigarette smoke exposure is a major determinant of adverse lung health, but the molecular processes underlying its effects on inflammation and immunity remain poorly understood. Therefore, we sought to understand whether inflammatory and host defense determinants are affected during subchronic cigarette smoke exposure. Dose-response and time course studies of lungs from Balb/c mice exposed to smoke generated from 3, 6, and 9 cigarettes/day for 4 days showed macrophage- and S100A8-positive neutrophil-rich inflammation in lung tissue and bronchoalveolar lavage (BAL) fluid, matrix metalloproteinase (MMP) and serine protease induction, sustained NF-kappaB translocation and binding, and mucus cell induction but very small numbers of CD3+CD4+ and CD3+CD8+ lymphocytes. Cigarette smoke had no effect on phospho-Akt but caused a small upregulation of phospho-Erk1/2. Activator protein-1 and phospho-p38 MAPK could not be detected. Quantitative real-time PCR showed upregulation of chemokines (macrophage inflammatory protein-2, monocyte chemoattractant protein-1), inflammatory mediators (TNF-alpha, IL-1beta), leukocyte growth and survival factors [granulocyte-macrophage colony-stimulating factor, colony-stimulating factor (CSF)-1, CSF-1 receptor], transforming growth factor-beta, matrix-degrading MMP-9 and MMP-12, and Toll-like receptor (TLR)2, broadly mirroring NF-kappaB activation. No upregulation was observed for MMP-2, urokinase-type plasminogen activator, tissue-type plasminogen activator, and TLRs 3, 4, and 9. In mouse strain comparisons the rank order of susceptibility was Balb/c > C3H/HeJ > 129SvJ > C57BL6. Partition of responses into BAL macrophages vs. lavaged lung strongly implicated macrophages in the inflammatory responses. Strikingly, except for IL-10 and MMP-12, macrophage and lung gene profiles in Balb/c and C57BL/6 mice were very similar. The response pattern we observed suggests that subchronic cigarette smoke exposure may be useful to understand pathogenic mechanisms triggered by cigarette smoke in the lungs including inflammation and alteration of host defense.

Fractionated, stereotactic proton beam treatment of cerebral arteriovenous malformations

OBJECTIVES

To evaluate the therapeutic efficiency and adverse effects of stereotactic proton beam treatment of cerebral arteriovenous malformations (AVM).

MATERIAL AND METHODS

Twenty-six patients treated in Uppsala during 1991-97 were included (men = 14, women = 12; mean age = 39, range = 23-64). The nidus volumes ranged from 0.3 to 102 ml (mean = 24, median = 13). The follow-up included clinical evaluation, magnetic resonance imaging (and/or computed tomography) every 6-12 months for 3 years and final angiography.

RESULTS

The volume changes at final follow-up in AVMs >25 ml were -89, -85, -44, -29, -7, 0, 0, +5 and +18 (%); in AVMs 11-24 ml, -100, -100, -97, -92 and 0 (%); and in AVMs <10 ml, -100, -100, -100, -100, -100, -99, -98, -50, -0 and +40 (%). Two patients were lost to follow-up due to cerebral haemorrhage and myocardial infarction. Radiology displayed significant perifocal oedema in one patient and slight oedema in four patients. Of nine patients with epilepsy, seven became seizure-free after therapy while two continued to suffer from seizures.

CONCLUSION

Proton beam irradiation is successful in a relatively high proportion of intermediate and large-sized cerebral AVMs. The adverse effects are acceptable. The advantage of proton treatment compared with gamma knife and LINAC stereotactic irradiation is that protons can irradiate even large volumes with a very sharp dose profile against normal surroundings. Thus, proton beam irradiation is a valuable option in the treatment of AVMs larger than 10 ml.

Cellular and cordless telephones and the risk for brain tumours

Microwave exposure from the use of cellular telephones has been discussed in recent years as a potential risk factor for brain tumours. We included in a case-control study 1617 patients aged 20-80 years of both sexes with brain tumour diagnosed between 1 January 1997 and 30 June 2000. They were alive at the study time and had histopathologically verified brain tumour. One matched control to each case was selected from the Swedish Population Register. The study area was the Uppsala-Orebro, Stockholm, Linköping and Göteborg medical regions of Sweden. Exposure was assessed by a questionnaire that was answered by 1429 (88%) cases and 1470 (91%) controls. In total, use of analogue cellular telephones gave an increased risk with an odds ratio (OR) of 1.3 (95% confidence interval (CI) 1.02-1.6). With a tumour induction period of >10 years the risk increased further: OR 1.8 (95% CI 1.1-2.9). No clear association was found for digital or cordless telephones. With regard to the anatomical area of the tumour and exposure to microwaves, the risk was increased for tumours located in the temporal area on the same side of the brain that was used during phone calls; for analogue cellular telephones the OR was 2.5 (95% CI 1.3-4.9). Use of a telephone on the opposite side of the brain was not associated with an increased risk for brain tumours. With regard to different tumour types, the highest risk was for acoustic neurinoma (OR 3.5, 95% CI 1.8-6.8) among analogue cellular telephone users.

Pain, coping, emotional state and physical function in patients with chronic radicular neck pain. A comparison between patients treated with surgery, physiotherapy or neck collar--a blinded, prospective randomized study

PURPOSE

To describe and explore the relationships between pain, emotional state and coping strategies in patients with chronic radicular neck pain before and after surgery or conservative treatments.

METHODS

We randomize 81 conseutive patients with cervical radicular pain and nerve root compression, verified by MRI, to either surgical decompression with fusion or physiotherapy or neck collar. Emotional state was both measured with Mood Adjective Check List. Hospital Anxiety and Depression Scale and with a Coping Strategies Questionnaire. Pain was measured with VAS and function with Disability Index Rating. Measurements were made before treatment, and follow ups after 3 and 12 months post treatment.

RESULTS

We found generally a low emotional state with anxiety, depression and sleep-disturbances not only connected to pain. Pain improved faster in the surgery group but after one year no differences were seen. Surgery and physiotherapy improved function with heavy work compared to collar after 3 months. Many patients used active coping before treatment, but after treatment more passive coping strategies were found.

CONCLUSION

We recommend a multidisciplinary rehabilitation with cognitive behavioural therapy and psychological interventions.

Expression of the IL-6 family cytokines in human brain tumors

In our RT-PCR screen for cytokine expression in human brain tumors we discovered increased levels of oncostatin M (OSM), ciliary neurotrophic factor (CNTF) and leukemia inhibitory factor (LIF), all belonging to the interleukin-6 (IL-6) cytokine family, in most of the tumors. The expression of these cytokines in normal adult brain tissue was found to be very low or below detection limit. OSM expression was elevated in most of the tumors and immunohistochemistry analysis showed that the tumor cells contained OSM in their cytoplasm, suggesting they produce this factor. Overexpression of OSM has not previously been reported in primary human brain tumors. The IL-6 cytokine family acts through a common gp130 receptor subunit that activates the JAK/STAT signaling pathway and therefore they have been suggested to have overlapping effects. Tissue inhibitor of metalloproteinase-1 (TIMP-1), matrix metalloproteinase 1 (MMP-1) and MMP-3 and IL-6 have been reported to be regulated by OSM. IL-6 was low or absent in the tumors. TIMP-1, MMP-1 and MMP-3 was expressed in most tumors but with no strict correlation to OSM levels.

Meningioma treated with interferon-alpha, evaluated with [(11)C]-L-methionine positron emission tomography

PURPOSE

In meningioma patients with postoperative residual masses, recurrent or primarily inoperable tumors, positron emission tomography (PET) with [(11)C]-L-methionine was used to evaluate treatment efficacy of IFN-alpha.

EXPERIMENTAL DESIGN

Twelve patients were treated with IFN-alpha at a dose of 1.5-5 million IU s.c. daily. PET, computed tomography, and/or magnetic resonance imaging were performed in all patients before and, at regular intervals, during IFN-alpha treatment. The ratio of tumor hot-spot uptake to cerebellar uptake or to cortex uptake was calculated. This ratio estimates the relative methionine accumulation in the tumor and presumably the proliferative activity in the tumor.

RESULTS

During IFN-alpha treatment, PET demonstrated a mean relative percentage of reduction in the uptake ratio (MRelR) of 22.3% in the meningiomas. In nine patients who were considered responders, defined as patients with a positive MRelR, the MRelR was 30.4%. For the three nonresponders, defined as patients with a negative MRelR, the MRelR was -1.8%. Three patients were followed for a long time: two patients for 8 years and one patient for 4 years and 6 months; the two patients followed for 8 years are still on IFN. The volumes of these tumors were constant or showed a slight decrease. No correlation was found between histopathological diagnosis (PAD) WHO grading I-III of meningiomas and response to IFN-alpha treatment.

CONCLUSIONS

PET was judged a useful method to predict which patients are suitable for long-term treatment with IFN-alpha and also for dose finding. In five patients treated from 9 months to 8 years, IFN-alpha seemed to be an effective oncostatic drug. The clinical usefulness of IFN-alpha, taking adverse reactions into account, must be evaluated in a larger series of patients.

Evaluation of the effect of high-energy proton irradiation treatment on meningiomas by means of 11C-L-methionine PET

A remnant meningioma of WHO grade I that is located at the base of the skull and is treated with radiotherapy has to be followed up for at least 5-10 years to evaluate the treatment effect and detect recurrence. The tumour has to grow considerably to show detectable volume increase on computed tomography (CT) or magnetic resonance imaging (MRI). Owing to the location at the base of the skull, a small increase in tumour volume may be hazardous. It is thus important to find a method to evaluate treatment effects earlier and potentially detect those tumours that have a tendency to grow. Nineteen patients with intracranial meningiomas were given irradiation with the 180-MeV proton beam at the Svedberg Laboratory, Uppsala, Sweden. The fractionation schedule used was in general a total dose of 24 Gy in four consecutive daily 6-Gy fractions. Serial 11C-Lmethionine PET examinations were used to evaluate the effect of stereotactic proton beam treatment. The radioactivity uptake in the tumour was evaluated as the ratio to the uptake in normal brain tissue. The follow-up period thus far is 36 months. In 15 of the 19 patients, 11C-L-methionine uptake was reduced 36 months after irradiation compared with the pre-treatment uptake of the tracer. In the total patient group the average reduction was 19.4%. Our results reveal that proton beam irradiation of meningiomas had an inhibitory effect on the methionine uptake in the meningiomas, although tumour size remained unchanged. The combination of unchanged tumour morphology and a reduction in methionine uptake after irradiation suggests that 11C-L-methionine PET might enable earlier evaluation of the treatment effect than is possible with CT or MRI.

Cognitive functioning and cerebrospinal fluid concentrations of neuropeptides for patients with good neurological outcomes after aneurysmal subarachnoid hemorrhage

OBJECTIVE

Many patients exhibit cognitive disturbances after aneurysmal subarachnoid hemorrhage (SAH). Structural and functional neuroimaging has failed to demonstrate any correlation with these complaints. This study was performed to investigate whether neuropeptide concentrations in cerebrospinal fluid could be related to cognitive disturbances after SAH.

METHODS

Lumbar cerebrospinal fluid was obtained, 3 to 6 months after surgery, from 17 patients who experienced good outcomes after aneurysmal SAH. The samples were analyzed for various neuropeptides using radioimmunoassays, and the peptide concentrations were evaluated in relation to scores on standardized neuropsychological tests.

RESULTS

The neuropsychological test results were normal for eight individuals, whereas the remaining nine patients exhibited various degrees of cognitive impairment. There was no correlation between the concentrations of arginine vasopressin or neuropeptide Y and test performance. However, significant correlations between cognitive impairment and elevated levels of beta-endorphins (P = 0.02), corticotropin-releasing factor (P = 0.004), and delta sleep-inducing peptide (P = 0.045) were noted.

CONCLUSION

Patients with cognitive impairments after aneurysmal SAH exhibited higher cerebrospinal fluid concentrations of endorphins, corticotropin-releasing factor, and delta sleep-inducing peptide than did those with normal capacity. This is probably attributable to diffuse derangement of transmitter release in the brain, resulting from the insult or ensuing complications, although a secondary increase in corticotropin-releasing factor concentrations caused by increased stress during the testing because of reduced cognitive capacity cannot be excluded.

Aggression: destructive and constructive aspects

The concept of aggression was long relegated to the shadow of the libido in psychoanalytic theory, placed among the negative affects by some theoreticians, denied the role of a primary drive among leading writers in clinical psychology, brought to the fore as an adaptive force in ethology, and proved to be a decisive factor in the development of psychosomatic ailments. The second part of the paper reviews experiments using projective techniques, showing that highly creative subjects as opposed to ones low in creativity seem inclined to accept their aggressive impulses. A total denial of these impulses has been typical of women with breast cancer.

Stereotactic irradiation of skull base meningiomas with high energy protons

Nineteen patients with inextirpable skull base meningioma with involvement of neurovascular structures were given irradiation with a 180 MeV proton beam at the The Svedberg Laboratory, Uppsala, Sweden. The patients were treated seated in a fixed position with a stereotactic approach. Titanium-markers to the outer table served for identification and verification of the target positioning for dose planning and irradiation. The patients were given a total dose of 24 Gy in four consecutive daily 6 Gy fractions. All patients have been followed for at least 36 months. So far no meningiomas have progressed after treatment. Two patients have developed corticosteroid responsive oedema in the target area 6 moths after treatment. Late, but not serious, symptoms of side effects have been observed in one patient.

Frontal lobe dysfunction in patients with non-frontal malignant gliomas: a monoaminergic dysregulation?

Previous investigations concerned with the neuropsychological function of patients with intracerebral supratentorial malignant gliomas has revealed the frequent occurrence of signs suggestive of an inhibitory frontal lobe dysfunction regardless of the intracerebral localization of the tumor and before the diagnosis was known to either the investigator or the patient. Upon closer analysis, the frontal lobe dysfunction has been verified by the demonstration of reduced blood flow in frontal areas in these patients. Since many of the findings can be related to a dysfunction of dopaminergic neurotransmission, we hypothesize that abnormal astrocytes interfere with the metabolism, transport and release of various neurotransmitters of which dopamine may be the one responsible for the most striking neuropsychological abnormalities in patients with malignant gliomas.

Temporal lobe epilepsy visualized with PET with 11C-L-deuterium-deprenyl--analysis of kinetic data

OBJECTIVES

The purpose of the study was to develop a simplified method for the acquisition and analysis of data from positron emission tomography (PET) using the ligand 11C-L-deuterium-deprenyl. This is motivated by an increased interest in methods to characterize gliosis in neurodegenerative diseases and epilepsy, which can be defined due to an increased expression of the enzyme MAO-B.

METHODS

Seven patients with temporal lobe epilepsy were investigated with PET. The tracer kinetics in different brain structures was recorded and analyzed using different models with and without a plasma input function. The derived values were correlated to literature values of 3H-deprenyl binding in frozen sections from normal human brains.

RESULTS

A good correlation was seen between in vivo binding and in vitro data, with the correlation being equally good irrespective of whether metabolite corrected plasma or modified cerebellar uptake values were used as input function. The epileptic lobe was, compared to non-epileptic, characterized by a lower initial distribution and an enhanced late accumulation of the tracer. With the applied method, it was possible to correctly identify the epileptic side in all 6 unilateral patients and I probable bilateral case.

CONCLUSIONS

PET with 11C-L-deuterium-deprenyl gives a good correlation between calculated in vivo binding and MAO-B activity. The analysis can be simplified and blood sampling avoided if modified cerebellar time-activity data is used as a reference. Separate images of distribution volume and MAO-B binding can be generated.

Long-term tacrine treatment in three mild Alzheimer patients: effects on nicotinic receptors, cerebral blood flow, glucose metabolism, EEG, and cognitive abilities

The effect of long-term treatment with tacrine (tetrahydroaminoacridine) was studied in three Alzheimer patients (aged 57, 64, and 68 years) with mild dementia. All three patients had a Mini-Mental State Examination score of 24/30 and carried at least one apolipoprotein E (ApoE) epsilon4 allele. Tacrine was given in doses between 80 and to 160 mg daily for 13-31 months. A lower tacrine concentration was observed generally in cerebrospinal fluid (CSF) compared with plasma. The acetylcholinesterase activity in CSF tended to be increased following longer periods of tacrine treatment, whereas the butyrylcholinesterase activity was decreased. The three patients repeatedly underwent positron emission tomography investigation of cerebral blood flow, nicotinic receptors, cerebral glucose metabolism, and electroencephalogram (EEG) and cognitive tests. Positive influences on these parameters were observed following both short-term and long-term treatment with tacrine. Improvement of nicotinic receptors (measured as 11C-nicotine binding), cerebral blood flow, EEG, and some cognitive tests (trail making test, block design test) occurred earlier after initiation of tacrine treatment compared with the glucose metabolism, which was increased after several months of tacrine treatment. An improvement in attention (trail making test) was observed following tacrine as sign for frontal lobe activation (EEG). The functional effects of tacrine in Alzheimer patients appeared to be related to both dose and length of cholinesterase inhibitor treatment.

Psychological profile related to malignant tumours of different histopathology

In a previous preoperative study of patients with gliomas, we made the original observation that patients with high grade as opposed to those with low-grade gliomas have a psychological profile marked by extreme emotional reactivity. In this postoperative study of the psychological profiles of patients with breast cancer, the main funding was unexpectedly analogous with the findings in the brain tumour study. The patients with poorly differentiated ductal carcinomas showed a specific and, compared to the patients with well differentiated carcinomas, outstanding psychological profile marked by extreme emotional reactivity as well as by genuine creativity. Some of the present patients with well differentiated carcinomas showed personality profiles marked by compulsive inhibition, also described earlier in the literature of patients with breast cancer. The psychobiological relations between emotional reactivity and aggressiveness of tumour growth are discussed.

Attitude towards aggression and creative functioning in patients with breast cancer

Three projective personality tests were used to assess attitude to aggression (The Identification Test), anxiety and defenses (The Meta-Contrast Technique) and creative functioning (The Creative Functioning Test) in 70 patients with breast cancer. Discriminant analyses were applied pro primo to characterize psychologically patients with a better prognosis and patients with a poorer prognosis. A second aim was to characterize psychologically older (postmenopausal) and younger (premenopausal) women. Generally, high scores on the Identification Test indicated maladaptive attitudes towards aggression among all the patients. Patients with a poorer prognosis showed responses that in healthy subjects indicate acknowledgement of aggressive impulses, perhaps suggesting lack of "defenses" against such impulses among those patients. Another way to describe it would be that patients with a better prognosis seem to have (normally nonadaptive) "defenses" against aggressive impulses while those with poorer prognosis have not. Surprisingly, the patients with a better prognosis (but not those with a poorer prognosis) gave responses classified as depression in the Meta-Contrast Technique. Typical of premenopausal patients were responses classified as anxiety as well as reaction formation on the Identification Test. Responses classified as adaptive defenses (isolation) were seen in the Meta-Contrast Technique. A surprising finding was that many of these patients were characterized by high scores on the creativity test. These original statistically significant findings of attitudes towards aggression and creative functioning in breast cancer patients are discussed in relation to the underlying nature of aggression and creativity.

Brain networks affected by synchronized sleep visualized by positron emission tomography

Nineteen lightly sleep-deprived healthy volunteers were examined with H2(15)O and positron emission tomography (PET). Scanning was performed during wakefulness and after the subjects had fallen asleep. Sleep stage was graded retrospectively from electroencephalogram (EEG) recordings, and scans were divided into two groups: wakefulness or synchronized sleep. Global flow was quantified, revealing no difference between sleep and wakefulness. A pixel-by-pixel-blocked one-way analysis of variance (ANOVA) was performed after correcting for differences in anatomy and global flow. The sum of squares of the z-score distribution showed a highly significant (P < 0.00001) omnibus difference between sleep and wakefulness. The z-score images indicated decreased flow in the thalamus and the frontal and parietal association cortices and increased flow in the cerebellum during sleep. A principal component (PC) analysis was performed on data after correction for global flow and block effects, and a multivariate analysis of variance (MANOVA) on all PC scores revealed significant (P = 0.00004) differences between sleep and wakefulness. Principal component's 2 and 5 correlated to sleep and revealed distinct networks consisting of PC 2, cerebellum and frontal and parietal association cortices, and PC 5, thalamus.

Positron emission tomography with 5-hydroxytryprophan in neuroendocrine tumors

PURPOSE

Carcinoid tumors, especially those of midgut origin, produce serotonin via the precursors tryptophan and 5-hydroxytryptophan (5-HTP). We have evaluated the usefulness of positron emission tomography (PET) with carbon-11-labeled 5-HTP in the diagnosis and treatment follow-up evaluation of patients with neuroendocrine tumors.

PATIENTS AND METHODS

PET using 11C-labeled 5-HTP was compared with computed tomography (CT) in 18 patients (14 midgut, one foregut, one hindgut carcinoid, and two endocrine pancreatic tumors [EPT]). In addition, 10 of 18 patients were monitored with PET examinations during treatment.

RESULTS

All 18 patients, including two with normal urinary 5-hydroxyindole acetic acid (U-5-HIAA), had increased uptake of 11C-labeled 5-HTP in tumorous tissue as compared with normal tissue. Liver metastases, as well as lymph node, pleural, and skeletal metastases, showed enhanced 5-HTP uptake and PET could detect more lesions than CT in 10 patients and equal numbers in the others. Tumor visibility was better for PET than for CT due to the high and selective uptake of 5-HTP with a high tumor-to-background ratio. Binding studies indicated an irreversible trapping of 5-HTP in the tumors. Linear regression analyses showed a clear correlation (r = .907) between changes in U-5-HIAA and changes in the transport rate constant for 5-HTP during treatment.

CONCLUSION

PET with 11C-labeled 5-HTP demonstrated high uptake in neuroendocrine gastrointestinal tumors and thereby allowed improved visualization compared with CT. The in vivo data on regional tumor metabolism, as expressed in 11C-5-HTP uptake and transport rate, provided additional information over conventional radiologic techniques. The close correlation between the changes in 11C-5-HTP transport rate and U-HIAA during medical treatment indicates the potential of 11C-5-HTP-PET as a means to monitor therapy.

Somatotopic organization along the central sulcus, for pain localization in humans, as revealed by positron emission tomography

Regional cerebral blood flow was measured with positron emission tomography (PET) in six healthy volunteers at rest and during experimentally induced, sustained cutaneous pain on the dorsum of the right hand or on the dorsum of the right foot. Pain was inflicted by intracutaneous injection of capsaicin, providing a mainly C-fibre nociceptive stimulus. Statistical analysis showed significant activations along the central sulcus (SI) area when comparing pain in the hand to pain in the foot. Separate comparison of both pain states to a baseline revealed different locations along the central sulcus for hand pain and foot pain. The encountered differences are consistent with what is previously known about the somatotopics of non-painful stimuli. When comparing painful stimuli to baseline, the contralateral anterior cingulate gyrus, the ipsilateral anterior insular cortex and the ipsilateral prefrontal cortex were implicated. The results are consistent with an involvement of SI in the spatial discrimination of acute cutaneous pain.

Do organic solvents induce changes in the dopaminergic system? Positron emission tomography studies of occupationally exposed subjects

OBJECTIVES

The objective of this study was to test the hypothesis that long-term occupational exposure to organic solvents may effect the levels and turnover of dopamine in man.

METHODS

A study was performed on 17 patients with neuropsychiatric symptoms due to occupational solvent exposure, and 11 healthy non-exposed male volunteers (controls). Positron emission tomography (PET) was used to assess striatal dopaminergic function, using L-[11C]DOPA, [11C]nomifensine and [11C]raclopride as tracers.

RESULTS

The rate of dopamine synthesis was significantly increased among subjects with occupational exposure to organic solvents compared with non-exposed controls. After controlling for the difference in age between exposed and controls, the effect of solvent exposure became less apparent and was reduced from +32% (P = 0.009) to +25% (P = 0.07). There were no differences with regard to the binding of [11C]nomifensine. Patients with and without the diagnosis of toxic encephalopathy did not differ with regard to their putaminal uptake of L-[11C]DOPA, [11C]nomifensine and [11C]raclopride.

CONCLUSION

The data support the hypothesis that long-term exposure to organic solvents may increase the rate of dopamine synthesis in the brain without affecting the number of presynaptic terminals or postsynaptic dopamine receptors.

Regional cerebral blood flow and oxygen metabolism during migraine with and without aura

Eleven cases of migraine with and without aura were investigated with positron emission tomography (PET). Regional cerebral blood flow (rCBF), oxygen metabolism (rCMRO2) and oxygen extraction (rOER) were measured during baseline (n = 11), aura (n = 6), headache (n = 10) and after treatment with sumatriptan (n = 4). Data were analysed using an ROI-based approach from 26 different anatomically defined regions, and also an exploratory approach whereby all subjects were normalized to a stereotactic brain atlas; t-maps were constructed by depicting significant changes between states. The exploratory approach revealed a region corresponding to the primary visual cortex with significant reductions in rCBF (23.1%) and rCMRO2 (22.5%), but no change in rOER during the headache phase compared to baseline. These data suggest that cerebral ischemia was not the primary cause of the attacks in these cases.

PET-methionine of skull base neuromas and meningiomas

Eighteen patients with intracranial skull base tumours diagnosed at CT or MR as neuromas or meningiomas were studied with positron emission tomography (PET) using L-(methyl-11C) methionine. Compared with normal cerebellar tissue, the uptake of methionine in the tumours increased more rapidly and reached a higher level, and showed a slow decline after a peak occurring about 5 min after the injection. All the meningiomas exhibited considerably higher accumulation of the tracer compared with the surrounding cerebellar tissue, which made the tumour easy to identify and to demarcate from the surrounding cerebellar tissue, which made the tumour easy to identify and to demarcate from the surrounding structures (tumour to cerebellum ratios 2.62-5.37, mean 3.63). The uptake was homogeneous in all meningiomas, which were all of the syncytial type. The neuromas showed lower contrast against the cerebellum (tumour to cerebellum ratios 1.1-1.87, mean 1.48). Some neuromas displayed an irregular pattern with regions of decreased tracer uptake corresponding to small cystic areas within the neuroma. There was no overlap in methionine uptake between the two tumour groups. The results indicate that PET-methionine may contribute to the evaluation, treatment planning and follow-up of patients with skull base meningiomas and neuromas.

Possible effects of tetrahydrobiopterin treatment in six children with autism--clinical and positron emission tomography data: a pilot study

Six children, between 3 and 5 years of age, having infantile autism according to DSM-III-R, were treated for 3 months with 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (R-BH4), a cofactor for tyrosine hydroxylases in the biosynthetic pathway of catecholamines and serotonin. A criterion for inclusion in the study was a relatively low level of R-BH4 in the cerebrospinal fluid. For clinical evaluation, the Parental Satisfaction Survey (PASS) was used every fourth week and the Griffiths Developmental Scales were used before starting and 3 months after completing the treatment. During the treatment period, all parents reported improvements in the child's social functioning-mainly eye contact and desire to interact-and in the number of words or sounds which the child used. Small positive changes were noted on the Griffiths Developmental Scales between the two testing occasions. R-BH4 levels in CSF increased significantly after treatment. The positron emission tomography (PET) study showed that the high value of dopamine D2 receptor binding in the caudate and putamen decreased by about 10% towards the normal level after treatment with R-BH4. The observations in this open study indicate that the drug might be useful for a subgroup of children with autism, but there is a need for a larger double-blind study with a longer treatment period.

Early mental changes in patients with astrocytomas with special reference to anxiety and epilepsy

This study of 47 patients with low- and high-grade gliomas retrospectively focuses on the patients' history with regard to affective and cognitive disturbances as well as to the presence of epileptic manifestations. Early emotional changes with a sudden onset were common in both patient groups, especially panic-like anxiety. It is suggested that patients with a high-grade glioma may present with affective disturbances with a sudden onset, while such disturbances in patients with low-grade gliomas could be of epileptiform origin. It is also suggested that the biochemical bases of anxiety and epilepsy in glioma patients could be analyzed to understand underlying biopsychological mechanisms of malignant brain tumors.

Simultaneous intracerebral microdialysis and positron emission tomography in the detection of ischemia in patients with subarachnoid hemorrhage

Intracerebral microdialysis (MD) was applied in patients with subarachnoid hemorrhage. The regional CBF, the CMRO2, and oxygen extraction ratio (OER) were measured with simultaneous positron emission tomography (PET). The aim was to directly correlate alterations in dialysate levels of energy-related metabolites (lactate, lactate/pyruvate ratio, hypoxanthine) and excitatory amino acids (EAAs) (glutamate and aspartate) to the energy state in the MD probe region as determined by PET. Regional ischemia was defined according to Heiss et al. and Lassen (Heiss et al., 1992; Lassen, 1966). Whole-brain ischemia was considered present when the OER for the whole brain exceeded the mean whole-brain OER + 2 SD of six reference patients. In general, the presence of whole-brain ischemia and/or regional ischemia within the region of the MD probe was associated with increased levels of energy-related metabolites and EAAs retrieved by MD. Increased levels of energy-related metabolites and EAAs were only occasionally seen when PET did not show any signs of ischemia or when signs of regional ischemia were found remote from the MD probe region. Thus, the energy-related metabolites and EAAs may be used as extracellular "markers" of ischemia. PET may be of use in defining critical ischemic regions (tissue at risk) where the MD probe can be inserted for chemical monitoring.

Activation PET scanning in pretreatment evaluation of patients with cerebral tumours or vascular lesions in or close to the sensorimotor cortex

Treatment of tumours and vascular lesions in or close to eloquent cortex may inflict neurological deficits. Intra-operative mapping procedures have been used for many decades in efforts to minimize neurological sequelae. The possibility for non-invasive pre-operative brain mapping has emerged with the advent of positron emission tomography (PET). In this paper we report on 11 patients with a tumour or vascular lesion in or close to the sensorimotor (10 patients) or visual cortex (one patient). The patients were subjected to activation PET scanning by means of vibrotactile or visual stimulation. The results show that in most of the patients the important relation between the lesion and the sensorimotor cortex could be determined. The patient with a lesion in the occipital lobe had involvement of the entire visual cortex as judged by comparison with activated areas on the nonlesion side.

Positron emission tomography with [11C]deuterium-deprenyl in temporal lobe epilepsy

We performed positron emission tomography (PET) with [11C]deuterium-deprenyl in 9 patients with temporal lobe epilepsy (TLE) undergoing evaluation for possible epilepsy surgery. Seven patients had unilateral and 2 had bilateral mesiotemporal epileptic foci based on the preoperative investigation including ictal EEG discharges and PET with 2-[18F]fluoro-2-deoxyglucose (FDG). Deprenyl is an irreversible inhibitor of monoamine oxidase type B (MAO-B) with a very high affinity for the enzyme. In the brain, MAO-B is preferentially located in astrocytes, and a previous in vitro study showed increased binding of the ligand in sclerotic hippocampi. Dynamically acquired N-[methyl-11C]-a,a-di-deutero-L-deprenyl distribution in PET images were analyzed graphically, and the focus regions were assessed visually on the PET images. In addition, the accumulation rate and distribution volume of the tracer relative to the cerebellar cortex were measured in standardized homologous temporal regions by semiquantitative methods. Uptake of [11C]deuterium-deprenyl was significantly increased in the epileptogenic temporal lobes, both apparently and semiquantitatively. By calculating mean interlobar ratios, we identified the temporal lobe containing the epileptic focus in six unilateral cases. One case was ambiguous but was not falsely localized. The two bilateral cases were correctly identified as such. Our results suggest that PET with [11C]deuterium-deprenyl might be a useful method for identification of epileptogenic temporal lobes.

Positron emission tomography studies in patients with locally advanced and/or metastatic breast cancer: a method for early therapy evaluation?

PURPOSE

To investigate if sequential positron emission tomographic (PET) scans with the glucose analog 18F-2-fluoro-2-deoxy-D-glucose (18FDG) and/or L-methyl-11C-methionine (11C-methionine) in patients with breast cancer could provide early information on the efficacy of polychemotherapy.

PATIENTS AND METHODS

Sixteen patients with breast cancer (11 with locally advanced tumors, three with recurrent disease in the contralateral breast, two of them with distant and regional metastases, and two with distant metastases) underwent a baseline and two follow-up PET scans after the first and third/fourth polychemotherapy course. Tumor response was determined clinically/radiographically after three/four polychemotherapy courses.

RESULTS

Five patients were investigated with 18FDG, seven with both 11C-methionine and 18FDG, and four with only 11C-methionine before polychemotherapy. 11C-methionine presented a more distinct visualization of primary/contralateral breast cancers in five of seven patients when compared with 18FDG. Twelve of 16 patients demonstrated a response using conventional methods after the third/fourth course of polychemotherapy. Eight of these 12 clinical responders had a significant decrease in tracer uptake at the first PET scan performed 6 to 13 days after the first polychemotherapy course, and these reductions were further augmented after the third/fourth course and corresponded to the conventional therapy evaluation (clinical examination, computed tomography [CT], ultrasonography, and mammography).

CONCLUSION

Our data indicate that PET may be of clinical value in predicting response to chemotherapy in patients with locally advanced breast cancer and/or metastatic disease earlier than any other method used.

Kinetic analysis of regional (S)(-)11C-nicotine binding in normal and Alzheimer brains--in vivo assessment using positron emission tomography

A compartment model has been developed and validated for the kinetic analysis of (S)(-)11C-nicotine binding in the brain including a compensation for the influence of regional cerebral blood flow (rCBF). The model was applied to eight patients with Alzheimer disease (AD) and three age-matched healthy volunteers who received intravenous injections of (S)(-)11C-nicotine and 11C-butanol. The uptake and time course of radioactivity in different brain regions were assessed by positron emission tomography (PET). The rate constant k2* was formulated by dividing the K2 rate constant for 11C-nicotine with the K1 rate constant for 11C-butanol and thereby minimizing the influence of CBF on the quantitated binding of 11C-nicotine. The rate constant k2* for 11C-nicotine giving a quantitative measure of binding in the brain tissue was significantly higher in the temporal and frontal cortices as well as in the hippocampus of AD brains as compared with controls, indicating deficits in specific nicotinic binding in these brain areas of AD patients. A significant and negative correlation was obtained between cognitive function (Mini-Mental State Examination) and k2* of 11C-nicotine in the temporal and frontal cortices as well as in the hippocampus. The described kinetic model allowed in vivo quantification of nicotinic receptor binding in brain, which will be of importance in the future for evaluation of diagnosis, progress of disease, as well as the therapeutic effects in the treatment of AD.

Effects of 6R-L-erythro-5,6,7,8-tetrahydrobiopterin on the dopaminergic and cholinergic receptors as evaluated by positron emission tomography in the Rhesus monkey

The effects of 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (R-THBP) on the central cholinergic and dopaminergic systems in the Rhesus monkey brain were investigated by positron emission tomography (PET) with the muscarinic cholinergic receptor ligands (N-[11C]methyl-benztropine) and dopaminergic receptor ligands selective for D1, D2, and D3 subtypes ([11C]SCH23390, N-[11C]methyl-spiperone, and (+)[11C]UH232, respectively). None of the doses (3, 10, and 30 mg/kg i.v.) of R-THBP used significantly affected the regional cerebral blood flow (rCBF as determined by Raichle's H(2)15O method), and 10 mg/kg of R-THBP had little effect on the regional cerebral metabolic rate of glucose (rCMRglc) in the Rhesus monkey brain, as assessed by the graphical [18F]fluoro-deoxyglucose method. The effect of R-THBP on the muscarinic cholinergic system was dose dependent; while 3 mg/kg of R-THBP did not significantly alter the uptake ratio of N-[11C]methylbenztropine in several brain regions to that in the cerebellum, 10 and 30 mg/kg of R-THBP significantly reduced the uptake ratio in the thalamus, as well as in the frontal and temporal cortices. None of the doses (3, 10, and 30 mg/kg i.v.) of R-THBP tested affected [11C]SCH23390 (dopamine D1 receptor) binding. However, the k3 value for N-[11C]methyl-spiperone (dopamine D2 receptor) binding, which represents the association rate X Bmax value, was significantly decreased in the striatum. The uptake ratio of (+)[11C]UH232 (dopamine D3 receptor) in the striatum to that in the cerebellum was also decreased by administration of R-THBP (3 and 30 mg/kg i.v.). These findings suggest that R-THBP acts on dopamine D2 and D3 receptors selectively without markedly affecting dopamine D1 receptor binding. Furthermore, the changes in cholinergic and dopamine D2 and D3 receptors in vivo can not be attributed to a change in rCBF but may depend on the action of R-THBP.

Patient positioning for fractionated precision radiation treatment of targets in the head using fiducial markers

When irradiating targets in the brain, an accurately localised dose is often needed. One crucial moment to achieve this is the positioning of the patient. We have developed a positioning method where the patient is immobilised with a bite block and a head mould, and where the position of the target is determined by X-ray imaging of fiducial markers that are placed in the patient's skull. A method for computing the transformation needed to move the target from the observed to the prescribed position and orientation is described. This method uses the information from two orthogonal X-ray images and takes measurement errors and data from three or more markers into account. Results from using the method clinically in proton beam therapy are given.

MR imaging in cerebral gliomas. Tissue component analysis in correlation with histopathology of whole-brain specimens

A comparative analysis between MR examinations and histopathologic whole-brain sections regarding tumour components was performed in 5 brain specimens from patients with malignant glial brain tumours. All cases were examined with MR imaging in vitro and in 2 cases a close comparison with the MR examinations in vivo was also possible. The most homogeneous hypercellular area in malignant gliomas, giving the highest tumour grade, was not visualised on MR imaging as an isolated entity, either in vitro or in vivo. The most conspicuous tumour component, reflecting the heterogeneity of malignant gliomas, was necrosis. This feature was best depicted in the T2WI. In 4 of 5 cases, distant tumour spread of benign-looking tumour cells was found in areas visualised as normal on T2WI, outside the margins of the peritumoural oedema. In 2 cases, estimation of water content was performed immunohistochemically and a close correlation was found in each case between peritumoural and periventricular hyperintensity on T2WI and areas of pallor on the haematoxylin-eosin-stained whole-brain sections. These areas corresponded to microscopical oedema. MR imaging reflects underlying heterogeneous histopathology in malignant gliomas. The degree of malignancy of the lesion as a whole can thus be assessed by MR imaging. However, the method does not allow malignant gliomas to be correctly delineated.

Non-synchronous behavior of neuronal activity, oxidative metabolism and blood supply during mental tasks in man

In near-infrared spectroscopic studies during mental tasks such as problem solving and mental arithmetic, we found that 9 of 33 healthy volunteers showed decreases in both the regional cerebral blood flow (r-CBF) and oxygen consumption rate (CMRO2) in the frontal region of the dominant hemisphere. To confirm these unexpected observations, we performed simultaneous measurements by positron emission tomography (PET) and near-infrared spectroscopy (NIRS) in two such subjects. PET images also showed that CBF decreased within the presumptive area illuminated by near-infrared light during mental task. However, CBF decreased in almost all regions while the subject gave a correct answer. Thus, the questions arose: Are mental tasks always associated with increases in r-CBF and/or CMRO2?