RNA expression profiling in depressed patients suggests retinoid-related orphan receptor alpha as a biomarker for antidepressant response

Response to antidepressant treatment is highly variable with some patients responding within a few weeks, whereas others have to wait for months until the onset of clinical effects. Gene expression profiling may be a tool to identify markers of antidepressant treatment response and new potential drug targets. In a first step, we selected 12 male, age- and severity-matched pairs of remitters and nonresponders, and analyzed expression profiles in peripheral blood at admission and after 2 and 5 weeks of treatment using Illumina expression arrays. We identified 127 transcripts significantly associated with treatment response with a minimal P-value of 9.41 × 10(-)(4) (false discovery rate-corrected). Analysis of selected transcripts in an independent replication sample of 142 depressed inpatients confirmed that lower expression of retinoid-related orphan receptor alpha (RORa, P=6.23 × 10(-4)), germinal center expressed transcript 2 (GCET2, P=2.08 × 10(-2)) and chitinase 3-like protein 2 (CHI3L2, P=4.45 × 10(-2)) on admission were associated with beneficial treatment response. In addition, leukocyte-specific protein 1 (LSP1) significantly decreased after 5 weeks of treatment in responders (P=2.91 × 10(-2)). Additional genetic, in vivo stress responsitivity data and murine gene expression findings corroborate our finding of RORa as a transcriptional marker of antidepressant response. In summary, using a genome-wide transcriptomics approach and subsequent validation studies, we identified several transcripts including the circadian gene transcript RORa that may serve as biomarkers indicating antidepressant treatment response.

Cost-effective GPU-grid for genome-wide epistasis calculations

BACKGROUND

Until recently, genotype studies were limited to the investigation of single SNP effects due to the computational burden incurred when studying pairwise interactions of SNPs. However, some genetic effects as simple as coloring (in plants and animals) cannot be ascribed to a single locus but only understood when epistasis is taken into account [1]. It is expected that such effects are also found in complex diseases where many genes contribute to the clinical outcome of affected individuals. Only recently have such problems become feasible computationally.

OBJECTIVES

The inherently parallel structure of the problem makes it a perfect candidate for massive parallelization on either grid or cloud architectures. Since we are also dealing with confidential patient data, we were not able to consider a cloud-based solution but had to find a way to process the data in-house and aimed to build a local GPU-based grid structure.

METHODS

Sequential epistatsis calculations were ported to GPU using CUDA at various levels. Parallelization on the CPU was compared to corresponding GPU counterparts with regards to performance and cost.

RESULTS

A cost-effective solution was created by combining custom-built nodes equipped with relatively inexpensive consumer-level graphics cards with highly parallel GPUs in a local grid. The GPU method outperforms current cluster-based systems on a price/performance criterion, as a single GPU shows speed performance comparable up to 200 CPU cores.

CONCLUSION

The outlined approach will work for problems that easily lend themselves to massive parallelization. Code for various tasks has been made available and ongoing development of tools will further ease the transition from sequential to parallel algorithms.

Investigation of 17 candidate genes for personality traits confirms effects of the HTR2A gene on novelty seeking

Genes involved in serotonergic and dopaminergic neurotransmission have been hypothesized to affect different aspects of personality, but findings from genetic association studies did not provide conclusive results so far. In previous studies, however, only one or a few polymorphisms within single genes were investigated neglecting the possibility that the genetic associations might be more complex comprising several genes or gene regions. To overcome this limitation, we performed an extended genetic association study analyzing 17 serotonergic (SLC6A4, HTR1A, HTR1B, HTR2A, HTR2C, HTR3A, HTR6, MAOA, TPH1, TPH2) and dopaminergic genes (SLC6A3, DRD2, DRD3, DRD4, COMT, MAOA, TH, DBH), which have been previously reported to be implicated with personality traits. One hundred and ninety-five single nucleotide polymorphisms (SNPs) within these genes were genotyped with the Illumina BeadChip technology (HumanHap300, Human-1) in a sample of 366 mentally healthy Caucasians. Additionally, we tried to replicate our results in an independent sample of further 335 Caucasians. Personality traits in both samples were assessed with the German version of Cloninger's Tridimensional Personality Questionnaire. From 30 SNPs showing associations at a nominal level of significance, two intronic SNPs, rs2770296 and rs927544, both located in the HTR2A gene, withstood correction for multiple testing. These SNPs were associated with the personality trait novelty seeking. The effect of rs927544 could be replicated for the novelty seeking subscale extravagance, and the same SNP was also associated with extravagance in the combined samples. Our results show that HTR2A polymorphisms modulate facets of novelty seeking behaviour in healthy adults suggesting that serotonergic neurotransmission is involved in this phenotype.

Acute stress regulation of neuroplasticity genes in mouse hippocampus CA3 area--possible novel signalling pathways

Stress exposure can lead to the precipitation of psychiatric disorders in susceptible individuals, but the molecular underpinnings are incompletely understood. We used forced swimming in mice to reveal stress-regulated genes in the CA3 area of the hippocampus. To determine changes in the transcriptional profile 4 h and 8 h after stress exposure microarrays were used in the two mouse strains C57BL/6J and DBA/2J, which are known for their differential stress response. We discovered a surprisingly distinct set of regulated genes for each strain and followed selected ones by in situ hybridisation. Our results support the concept of a phased transcriptional reaction to stress. Moreover, we suggest novel stress-elicited pathways, which comprise a number of genes involved in the regulation of neuronal plasticity. Furthermore, we focused in particular on dihydropyrimidinase like 2, to which we provide evidence for its regulation by NeuroD, an important factor for neuronal activity-dependent dendritic morphogenesis.

RLS3: Fine-mapping of an autosomal dominant locus in a family with intrafamilial heterogeneity

A new locus for restless legs syndrome (RLS3) was identified on chromosome 9p24-22. The authors analyzed transmission disequilibrium tests (TDTs) and affecteds-only linkage analysis in one large family of Bavarian origin, taking into account age at onset. P values were 0.0054 for marker D9S1810 for TDT and 0.0009 for the affecteds-only linkage analysis, providing a confirmation of RLS3. This study narrows the region containing the autosomal dominant RLS3 locus to 11.1 cM (16.6 Mbp).

Fiber tracking from DTI using linear state space models: detectability of the pyramidal tract

Diffusion tensor imaging (DTI) is an emerging and promising tool to provide information about the course of white matter fiber tracts in the human brain. Based on specific acquisition schemes, diffusion tensor data resemble local fiber orientations allowing for a reconstruction of the fiber bundles. Current techniques to calculate fascicles range from simple heuristic tracking solutions to Bayesian and differential equations approaches. Most methods are based only on local diffusion information, often resulting in bending or kinking fiber paths in voxels with reduced diffusion properties. In this article we present a new tracking approach based on linear state space models encompassing an inherent smoothness criterion to avoid too wiggly tracked fiber bundles. The new technique will be described formally and tested on simulated and real data. The performance tests are focused on the pyramidal tract, where we employed a test-retest study and a group comparison in healthy subjects. Anatomical course was confirmed in a patient with selective degeneration of the pyramidal tract. The potential of the presented technique for improved neurosurgical planning is demonstrated by visualization of a tumor-induced displacement of the motor pathways. The paper closes with a thorough discussion of perspectives and limitations of the new tracking approach.

Frequency dependence and gender effects in visual cortical regions involved in temporal frequency dependent pattern processing

Neural response to flickering stimuli has been shown to be frequency dependent in the primary visual cortex. Controversial gender differences in blood oxygen level dependent (BOLD) amplitude upon 6 and 8 Hz visual stimulation have been reported. In order to analyze frequency and gender effects in early visual processing we employed a passive graded task paradigm with a dartboard stimulus combining eight temporal frequencies from 0 to 22 Hz in one run. Activation maps were calculated within Statistical Parametric Mapping, and BOLD amplitudes were estimated for each frequency within the striate and extrastriate visual cortex. The BOLD amplitude was found to steadily rise up to 8 Hz in BA 17 and 18 with an activation plateau at higher frequencies. In addition, we observed a laterality effect in the striate cortex with higher BOLD contrasts in the right hemisphere in men and in women. BOLD response rises similarly in men and women up to 8 Hz but with lower amplitudes in women at 4, 8, and 12 Hz (30% lower). No frequency effect above 1 Hz was found in the extrastriate visual cortex. There was also a regional specific gender difference. Men activated more in the right lingual gyrus (BA 18) and the right cerebellum compared with women, whereas women showed more activation in the right inferior temporal gyrus (BA 17). The study indicates that frequency dependent processing at the cortical level is limited to the striate cortex and may be associated with a more global information processing (right hemisphere dominance), particularly in men. The finding of significantly lower BOLD amplitudes in women despite previously shown larger VEP (visual evoked potential) amplitudes might suggest gender differences in cerebral hemodynamics (baseline rCBV, rCBF, or neurovascular coupling). The regional distinction points at additional differences in psychological processing even when using a simple visual stimulus.

Gray matter-changes and correlates of disease severity in schizophrenia: a statistical parametric mapping study

Voxel-based morphometry has recently been used successfully to detect gray matter volume reductions in schizophrenic patients. The aim of the present study was to confirm the findings on gray-matter changes and to complement these by applying the methodology to CSF-differences. Also, we wanted to determine whether a correlation exists between a clinically defined parameter of disease severity and brain morphology in schizophrenic patients. We investigated 48 schizophrenic patients and compared them with 48 strictly age- and sex-matched controls. High-resolution whole-brain MR-images were segmented and analyzed using SPM99. In a further analysis, the covariate effect of the global assessment of functioning-score (GAF) was calculated. Main findings were (i) left-dominant frontal, temporal, and insular GM-reductions and (ii) GM-increases in schizophrenic patients in the right basal ganglia and bilaterally in the superior cerebellum; (iii) CSF-space increases in patients complementary to some GM-reductions; (iv) a correlation between the GAF-score and local GM-volume in the left inferior frontal and inferior parietal lobe of schizophrenic patients. This study confirms and extends some earlier findings on GM-reduction and detected distinct GM-increases in schizophrenic patients. These changes were corroborated by complementary CSF-increases. Most importantly, a correlation could be established between two particular gray matter-regions and the overall disease severity, with more severely ill patients displaying a local GM-deficit. These findings may be of potentially large importance for both the future interpretation and design of neuroimaging studies in schizophrenia and the further elucidation of possible pathophysiological processes occurring in this disease.

Altered white and gray matter metabolism in CADASIL: a proton MR spectroscopy and 1H-MRSI study

OBJECTIVE

Subcortical white matter hyperintensities (WMH) and small cystic lesions are the radiologic hallmark of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a hereditary angiopathy causing stroke in young adults. To further characterize the cerebral pathology in vivo we analyzed metabolite concentrations in normal and abnormal appearing brain tissue using single and multiple voxel proton MR spectroscopy (1H-MRS and 1H-MRSI).

METHODS

Twenty patients with CADASIL and 21 age-matched controls were studied with 1H-MRSI at the level of the centrum semiovale; short echo time 1H-MRS was performed in six patients (WMH) and 10 controls. LCModel fits were used to estimate absolute and relative concentrations of N:-acetylaspartate (NAA), choline-containing compounds (Cho), total creatine (Cr) within WMH, normal appearing white matter (NAWM), and cortical gray matter (GM) as well as myo-inositol (mI) and lactate in WMH.

RESULTS

1H-MRSI-Patients with CADASIL showed significantly reduced NAA, Cho, Cr, and total metabolite content (Met(tot)) in WMH and NAWM. Normalization to Met(tot) revealed that NAA/Met(tot) was reduced in all regions, whereas Cho and Cr were relatively elevated in WMH. Short echo time 1H-MRS showed decreased NAA, Cr, Met(tot), and NAA/Met(tot) and elevated mI/Met(tot) and lactate in WMH. Metabolite changes were larger in severely affected subjects. Rankin scores correlated negatively with NAA/Met(tot) (all regions) and NAA/Cho (WMH), and positively with Cho/Met(tot) (WMH) and Cr/Met(tot) (NAWM).

CONCLUSION

Marked metabolic abnormalities were observed in abnormal and normal appearing white matter in patients with CADASIL. The findings suggest axonal injury, enlarged extracellular spaces, myelin loss, and gliosis. The cortical abnormalities may reflect structural damage or functional neuronal impairment secondary to white matter pathology. NAA reductions were correlated with clinical disability emphasizing the clinicopathologic relevance of axonal injury in CADASIL.

Differential lesion patterns in CADASIL and sporadic subcortical arteriosclerotic encephalopathy: MR imaging study with statistical parametric group comparison

PURPOSE

To differentiate lesion patterns in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) from those in patients with sporadic subcortical arteriosclerotic encephalopathy (sSAE).

MATERIALS AND METHODS

Magnetic resonance (MR; T2-weighted and fluid-attenuated inversion-recovery) images obtained in 28 patients with CADASIL were compared with images obtained in 24 patients with sSAE by using an automated pixel-based group comparison with statistical parametric mapping and regional semiquantitative rating.

RESULTS

Visual rating showed higher lesion scores for CADASIL in the temporal and temporopolar white matter (WM). Statistical parametric mapping group analysis independently revealed more extensive bilateral involvement of the anterior temporal and superior frontal WM in CADASIL. There were bilateral signal intensity reductions within the dentate nucleus, deep cerebellar WM, crus cerebri, and thalamus. Lesions extended remarkably more often into arcuate fibers in the temporopolar and paramedian superior frontal lobes in CADASIL. Linear discriminant analysis was used to classify 96% (50 of 52) of the cases correctly, with temporopolar WM and arcuate fiber involvement contributing most to the discrimination function.

CONCLUSION

The presented MR imaging criteria are useful in the diagnostic work-up in patients with leukoencephalopathy and help to differentiate CADASIL from sSAE. The observed pattern of vulnerability in CADASIL suggests future directions for research in the pathophysiology of this disorder. In addition, the study demonstrates the potential of automated image analysis to explore MR imaging lesion patterns.

Primary cutaneous follicle center cell lymphoma with follicular growth pattern

Cutaneous B-cell infiltrates showing a prominent follicular growth pattern with germinal centers are thought by some authors to represent either marginal zone lymphomas with reactive germinal centers or pseudolymphomas. To establish whether a true primary cutaneous follicular lymphoma exists, we studied biopsies from 15 patients with skin lesions characterized histopathologically by the presence of B-cell infiltrates with follicular pattern. Staging investigations, including bone marrow biopsy, were negative in all patients. All were negative for bcl-2 protein expression and did not present the t(14;18). In all biopsy specimens neoplastic follicles showed 1 or more morphologic or immunophenotypic criteria of malignancy (presence of a reduced mantle zone, absence of tingible body macrophages, reduced proliferation rate). In 9 specimens a monoclonal rearrangement of J(H) genes could be detected by polymerase chain reaction analysis. After laser beam microdissection, a band of the same length could be observed in 6 probes from different follicles from the same specimen, indicating the presence of the same monoclonal population of follicle center cells. Follow-up examinations in all patients revealed no evidence of extracutaneous spread (mean follow-up, 48.7 months). Our study demonstrates that primary cutaneous follicular lymphoma represents a distinct entity of the cutaneous B-cell lymphomas. (Blood. 2000;95:3922-3928)

Monoclonality of intraepidermal T lymphocytes in early mycosis fungoides detected by molecular analysis after laser-beam-based microdissection

The identification of neoplastic lymphocytes in early lesions of mycosis fungoides is difficult because of the scarcity of the infiltrate and the presence of reactive T lymphocytes admixed with neoplastic cells. Molecular analysis of the T cell receptor gene rearrangement using the polymerase chain reaction technique demonstrates monoclonality only in a proportion of these cases. The exact location of the malignant clone is unknown, and at present it is not clear whether neoplastic cells in early lesions reside within the epidermis, the superficial dermis, or both. We analyzed skin lesions from five patients with early mycosis fungoides using the polymerase chain reaction technique after microdissection of the specimens. In each case the epidermis was separated from the dermis using a laser-beam microdissection technique. Three samples were prepared from each lesion: one containing only the epidermis, one only the superficial dermis, and one the entire specimen. A distinct band could be observed in the epidermal sample in four cases, indicating the presence of an intraepidermal monoclonal population of T lymphocytes. The dermal sample revealed a monoclonal pattern in two cases (both of them showing clonality also within the epidermis). Analysis of the entire specimen revealed a monoclonal pattern only in two cases. Our results demonstrate that intraepidermal lymphocytes in early mycosis fungoides often show a monoclonal pattern of T cell receptor gene rearrangement. Microdissection of biopsy specimens may enhance the sensitivity of the polymerase chain reaction technique.

Reduced glutamate in the anterior cingulate cortex in depression: an in vivo proton magnetic resonance spectroscopy study

BACKGROUND

Functional imaging studies suggest a specific role of the anterior brain regions in the pathogenesis of major depression. The aim of this study was to evaluate possible neurochemical alterations in the frontomesial cortex in patients with major depressive episode using in vivo proton magnetic resonance spectroscopy ((1)H-MRS).

METHODS

Single voxel (1)H-MRS was performed in 19 patients with major depressive episodes and 18 age-matched healthy controls within the anterior cingulate cortex and the parietal white matter. Absolute concentrations were estimated for N-acetyl-aspartate, choline-containing compounds, total creatine, myo-inositol, unresolved glutamate and glutamine (Glx) and glutamate alone (Glu). Voxel composition was analyzed by image segmentation into cerebrospinal fluid (CSF), grey and white matter.

RESULTS

MANOVA test for Glx and Glu using age, percent CSF and percent grey matter contribution as covariates yielded a significant group effect within the anterior cingulate due to decrease of Glx in patients (-10.4%, p =.013). Considering only severely depressed patients, both Glx and Glu (-14.3%, p =.03) showed a significant decrease. There was no significant group effect for the neuronal marker NAA, creatine, choline or myo-inositol in either localization.

CONCLUSIONS

This study suggests a possible role of altered glutamatergic neurotransmission within the anterior cingulate in the pathogenesis of mood disorders. The otherwise unremarkable findings of major brain metabolites confirms lack of neurodegenerative or membrane metabolic changes in major depression.

Human cerebellar activity reflecting an acquired internal model of a new tool

Theories of motor control postulate that the brain uses internal models of the body to control movements accurately. Internal models are neural representations of how, for instance, the arm would respond to a neural command, given its current position and velocity. Previous studies have shown that the cerebellar cortex can acquire internal models through motor learning. Because the human cerebellum is involved in higher cognitive function as well as in motor control, we propose a coherent computational theory in which the phylogenetically newer part of the cerebellum similarly acquires internal models of objects in the external world. While human subjects learned to use a new tool (a computer mouse with a novel rotational transformation), cerebellar activity was measured by functional magnetic resonance imaging. As predicted by our theory, two types of activity were observed. One was spread over wide areas of the cerebellum and was precisely proportional to the error signal that guides the acquisition of internal models during learning. The other was confined to the area near the posterior superior fissure and remained even after learning, when the error levels had been equalized, thus probably reflecting an acquired internal model of the new tool.

Cutaneous involvement in lymphoblastic lymphoma

Lymphoblastic leukemia/lymphoma (LBL) is a malignant neoplasm of precursor lymphocytes of B- or T-cell phenotype. Involvement of the skin is relatively uncommon. We examined retrospectively the clinicopathologic, immunophenotypic, and molecular genetic features of six patients with cutaneous involvement of LBL (B-LBL=5; T-LBL=1). Patients presented clinically with solitary, large tumors located on the head (3 cases) or the back (1 case), or with generalized tumors (2 cases). Ulceration was uncommon. In two patients the onset of skin lesions was concomitant to the diagnosis of lymphoblastic leukemia. Histopathologic examination showed in all cases a dense, diffuse, monomorphous infiltrate located in the entire dennis and subcutaneous fat. A typical "starry sky" pattern was observed in the majority of the lesions. In some areas neoplastic cells were aligned in a "mosaic-like" fashion. Cytomorphologically, medium sized lymphoid cells with round or convoluted nuclei, inconspicuous nucleoli and scant cytoplasm predominated. There were no significant differences in the histopathologic features of skin lesions in T- and B-LBL. In B-LBL, CD79a was more useful than CD20 in determining the phenotype of neoplastic cells (4/5 cases positive for CD79a as compared to 2/5 cases positive for CD20). TdT, CD10 and CD43 were positive in 4 cases, CD34 in 2. The case of T-LBL revealed positivity for CD1a, CD3, CD43 and TdT, and negativity for CD34 and for B-cell markers. All neoplasms were positive for CD99 and bcl-2, and showed a high proliferation rate. Molecular genetic analysis of J(H) and T-cell receptor (TCR) genes performed using a polymerase chain reaction technique revealed a monoclonal rearrangement of J(H) genes in all five B-LBLs. One of these cases showed also a concomitant TCR-gamma gene rearrangement. A monoclonal rearrangement of the TCR-gamma gene was detected in the case of T-LBL. Our study shows that skin lesions of LBL present characteristic clinicopathologic and molecular features allowing the differentiation from other cutaneous lymphomas, even in cases without clinical history of previous precursor lymphoblastic leukemia/lymphoma.

Presupplementary motor area activation during sequence learning reflects visuo-motor association

In preceding studies (Hikosaka et al., 1996; Sakai et al., 1998) we have shown that the presupplementary motor area (pre-SMA), an anterior part of the medial premotor cortex, is active during visuo-motor sequence learning. However, the paradigm required the subjects first to acquire correct visuo-motor association and then to acquire correct sequence, and it was still unknown which of the two processes the pre-SMA is involved in. To further characterize the role of pre-SMA, we have conducted another series of functional magnetic resonance imaging experiments using three learning paradigms. The three were the same in that they involved a visuo-motor association component, but they differed in terms of the involvement of sequential components; one involved no sequence learning, whereas the other two involved learning of motor sequence or perceptual sequence. Comparison of the learning conditions with the any-order button press condition revealed pre-SMA activation in all three paradigms. The pre-SMA activation remained unchanged during learning of visuo-motor associations but decreased during learning of sequences, suggesting that the pre-SMA is related to visuo-motor association rather than sequence. The decrease of pre-SMA activation in the sequential paradigms may reflect the process by which individual visuo-motor associations were replaced by the formation of sequential procedural memory, which occurs outside the pre-SMA. Thus activation of the pre-SMA was related to the extent to which the task performance depended on conscious visuo-motor associations.

Functional magnetic resonance imaging of neural activity related to orthographic, phonological, and lexico-semantic judgments of visually presented characters and words

Functional magnetic resonance imaging was used to investigate neural activity during the judgment of visual stimuli in two groups of experiments using seven and five normal subjects. The subjects were given tasks designed differentially to involve orthographic (more generally, visual form), phonological, and lexico-semantic processes. These tasks included the judgments of whether a line was horizontal, whether a pseudocharacter or pseudocharacter string included a horizontal line, whether a Japanese katakana (phonogram) character or character string included a certain vowel, or whether a character string was meaningful (noun or verb) or meaningless. Neural activity related to the visual form process was commonly observed during judgments of both single real-characters and single pseudocharacters in lateral extrastriate visual cortex, the posterior ventral or medial occipito-temporal area, and the posterior inferior temporal area of both hemispheres. In contrast, left-lateralized activation was observed in the latter two areas during judgments of real- and pseudo-character strings. These results show that there is no katakana "word form center" whose activity is specific to real words. Activation related to the phonological process was observed, in Broca's area, the insula, the supramarginal gyrus, and the posterior superior temporal area, with greater activation in the left hemisphere. These activation foci for visual form and phonological processes of katakana also were reported for the English alphabet in previous studies. The present activation showed no additional areas for contrasts of noun judgment with other conditions and was similar between noun and verb judgment tasks, suggesting two possibilities: no strong semantic activation was produced, or the semantic process shared activation foci with the phonological process.

Separate cerebellar areas for motor control

Cerebellar activation was measured using functional magnetic resonance imaging, while seven normal subjects tapped their fingers paced by tone sequences with or without tone omission. The cerebellar anterior lobe (Larsell's H IV-V) ipsilateral to the movement was activated to a similar degree irrespective of the presence or absence of the tone omission. In contrast, the lateral part of the bilateral posterior lobe (H VIIa) was significantly highly activated for the tone sequence with random omission, compared with either that without omission or that with regular omission. The result suggests that the H IV-V is involved in motor execution, while the lateral part of H VIIa is involved in on-line motor adjustment to unpredictable sensory stimuli.

Localizing the site of magnetic brain stimulation by functional MRI

In order to locate the site of action of transcranial magnetic stimulation (TMS) within the human motor cortices, we investigated how the optimal positions for evoking motor responses over the scalp corresponded to the hand and leg primary-motor areas. TMS was delivered with a figure-8 shaped coil over each point of a grid system constructed on the skull surface, each separated by 1 cm, to find the optimal site for obtaining motor-evoked potentials (MEPs) in the contralateral first dorsal interosseous (FDI) and tibialis anterior (TA) muscles. Magnetic resonance imaging scans of the brain were taken for each subject with markers placed over these sites, the positions of which were projected onto the cortical region just beneath. On the other hand, cortical areas where blood flow increased during finger tapping or leg movements were identified on functional magnetic resonance images (fMRI), which should include the hand and leg primary-motor areas. The optimal location for eliciting MEPs in FDI, regardless of their latency, lay just above the bank of the precentral gyrus, which coincided with the activated region during finger tapping in fMRI studies. The direction of induced current preferentially eliciting MEPs with the shortest latency in each subject was nearly perpendicular to the course of the precentral gyrus at this position. The optimal site for evoking motor responses in TA was also located just above the activated area during leg movements identified within the anterior portion of the paracentral lobule. The results suggest that, for magnetic stimulation, activation occurs in the primary hand and leg motor area (Brodmann area 4), which is closest in distance to the optimal scalp position for evoking motor responses.

Transition of brain activation from frontal to parietal areas in visuomotor sequence learning

We studied the neural correlates of visuomotor sequence learning using functional magnetic resonance imaging (fMRI). In the test condition, subjects learned, by trial and error, the correct order of pressing two buttons consecutively for 10 pairs of buttons (2 x 10 task); in the control condition, they pressed buttons in any order. Comparison between the test condition and the control condition revealed four brain areas specifically related to learning: the dorsolateral prefrontal cortex (DLPFC), the presupplementary motor area (pre-SMA), the precuneus, and the intraparietal sulcus (IPS). We found that the time course of activation during learning was different between these areas. To normalize the individual differences in the speed of learning, we classified the performance of each subject into three learning stages: early, intermediate, and advanced stages. Both the relative increase of signal intensity and the number of activated pixels within the four areas showed significant changes across the learning stages, with different time courses. The two frontal areas, DLPFC and pre-SMA, were activated in the earlier stages of learning, whereas the two parietal areas, precuneus and IPS, were activated in the later stages. Specifically, DLPFC, pre-SMA, precuneus, and IPS were most highly activated in the early stage, in both the early and intermediate stages, in the intermediate stage, and in both the intermediate and advanced stages, respectively. The results suggest that the acquisition of visuomotor sequences requires frontal activation, whereas the retrieval of visuomotor sequences requires parietal activation, which might reflect the transition from the declarative stage to the procedural stage.

Primary cutaneous marginal zone B-cell lymphoma: a recently described entity of low-grade malignant cutaneous B-cell lymphoma

Recently a new classification of primary cutaneous B-cell lymphomas (PCBCLs) has been proposed by the European Organization for Research and Treatment of Cancer (EORTC)--Cutaneous Lymphoma Project Group. The marginal zone B-cell lymphomas (MZLs) were not included as a distinct entity because of insufficient experience and controversial opinions. We have studied 32 patients (M:F ratio 1.5:1; age range 25-93 years; mean age 49.6 years; median age 50 years) to determine the diagnostic criteria of primary cutaneous MZL and the relationship with other low-grade malignant PCBCLs. For comparison, three patients with immunocytoma were included in the study. Clinically, patients presented with solitary or clustered reddish or red-brown papules, nodules, and plaques, sometimes surrounded by an erythematous halo. Histopathologic sections showed nodular or diffuse infiltrates involving the dermis and subcutaneous fat. Cytomorphologically small to medium-sized cells with indented nuclei and abundant pale cytoplasm (marginal zone cells, centrocyte-like cells) predominated. In addition, scattered blasts, lymphoplasmacytoid cells, and plasma cells were observed below the epidermis and at the periphery of the infiltrates. Reactive germinal centers were present in 75% of the cases. The three cases of immunocytoma showed a more monomorphous pattern with predominance of lymphoplasmacytoid cells. The marginal zone cells showed a CD20+, CD79a+, CD5- and Bcl-2+ immunophenotype. They expressed immunoglobulin G in the majority of the cases. Staining with the monocytoid B cell-related antibody KiM1p gave positive results in all specimens with a typical intracytoplasmic granular pattern. A monoclonal distribution of immunoglobulin light chains was observed in marginal zone cells in 75% of the cases. Germinal centers, when present, were either polyclonal or negative for both kappa and lambda light chains. Monoclonal rearrangement of the JH gene was detected via polymerase chain reaction (PCR) in 18 of 26 investigated specimens. Analysis in 12 patients of the bcl-2/immunoglobulin heavy chain gene rearrangement using PCR yielded negative results. Lesions were treated by surgical excision followed in some patients by local radiotherapy. Systemic antibiotic therapy was administered to three patients, with good response in two. The prognosis is excellent. After a mean follow-up of 47.9 months (range 6-252; median 24) all patients are alive without signs of systemic lymphoma. Primary cutaneous MZL represents a distinct clinicopathologic subtype of low-grade malignant PCBCL.

Self-sustained sequence replication (3SR): an alternative to PCR

The amplification of target nucleic acids before hybridization is one of the most powerful approaches for the detection of low copy number RNA and DNA. The best known amplification reaction is PCR which has many applications. However, certain drawbacks of the PCR reaction provide a role for alternative amplification methods. One of these methods is the self-sustained sequence replication (3SR) reaction, which is an isothermal method for RNA amplification depending on the action of three enzymes. 3SR has been used in several in vitro applications and has also been modified for in situ use (IS-3SR). We have studied IS-3SR with the measles virus as a model and have found that it can significantly amplify the amount of intracellular RNA. Such a level of amplification could raise the amount of single copy RNA to the level of detection by conventional in situ hybridization. Although careful controls to insure its specificity must be carried out, IS-3SR has several advantages, including ease of use, preserved cell morphology, and specificity for RNA amplification, which make it an attractive alternative to the in situ PCR method.

Infection by Borrelia burgdorferi and cutaneous B-cell lymphoma

In past years, association of primary cutaneous B-cell lymphoma (CBCL) with infection by Borrelia burgdorferi has been reported in a few patients. The evidence for a pathogenetic role was based on clinical grounds or raised titre of antibodies in serum. Both methods, however, do not prove the association between the micro-organism and the CBCL, especially in countries where infection by Borrelia burgdorferi is endemic. Moreover, the exact percentage of Borrelia burgdorferi-positive CBCL is not known. We retrieved from our files 50 cases of CBCL to perform PCR analysis of Borrelia burgdorferi DNA on paraffin-embedded tissue sections. Only patients with primary CBCL were selected. In all cases, monoclonality of the infiltrate was confirmed by immunohistological pattern of immunoglobulin light chains or molecular analysis of JH gene rearrangement, or both. Specific DNA sequences of Borrelia burgdorferi were identified in cutaneous lesions from 9 patients (follicle center lymphoma: 3/20; immunocytoma: 3/4; marginal zone B-cell lymphoma: 2/20; diffuse large B-cell lymphoma: 1/6). Specificity was confirmed by Southern blot hybridisation in all positive cases. We could show that Borrelia burgdorferi DNA is present in skin lesions from a small proportion of patients (18%) with various types of CBCL. Our results may have therapeutic implications. In analogy to Helicobacter pylori-associated MALT-lymphomas, which in some cases can be cured by eradication of Helicobacter pylori infection, a proportion of CBCL may be cured with antibiotic therapy against Borrelia burgdorferi. Although yet speculative, adequate antibiotic treatment for patients with primary CBCL should be considered before more aggressive therapeutic options are applied, particularly in countries where infection by Borrelia burgdorferi is endemic. PCR analysis of Borrelia burgdorferi DNA is a fast test that should be performed in all patients with CBCL to identify those who more likely could benefit from an early antibiotic treatment.

Laser beam microdissection in the diagnosis of cutaneous B-cell lymphoma

Interpretation of molecular analyses of cutaneous lymphoid infiltrates may be difficult because a heterogeneous group of cells in usually present within the neoplasms. Extraction of DNA from tissue sections does not provide exact information about which cell population has been analysed. We present a laser microscope system that allows selective molecular analysis of single cells or small groups of cells in cases of cutaneous lymphoma. An ultraviolet (UV)-laser microscope system (PALM, Wolfratshausen, Germany) was used to isolate particular populations of cells from a routinely processed specimen of a cutaneous follicular lymphoid proliferation. Using the UV-laser beam, a circle was cut around a target germinal centre in order to separate it from neighbouring tissues and to isolate a pure population of germinal centre cells. Isolated cells were scraped off with a micromanipulator and placed in a proteinase-K solution. DNA was extracted and amplified by the polymerase chain reaction (PCR) technique. Analysis of immunoglobulin JH gene rearrangement showed a distinct monoclonal band. In a second phase, using the same procedure in the same specimen, mantle zone cells around a germinal centre and single interfollicular B lymphocytes were isolated for PCR analysis of immunoglobulin JH gene rearrangement. In this population of cells, no clonality could be detected. This new technique allows the selective elimination of undesired cells and tissue from cutaneous neoplasms. By destruction of unwanted tissues with laser-beam energy a contamination-free sample is obtained. Analysis of isolated cells in our case demonstrated a clonal rearrangement derived from germinal centre cells and not from other B lymphocytes in the specimen, confirming the diagnosis of cutaneous follicle centre lymphoma. The method described has exciting implications for dermatology and dermatopathology, allowing precise correlation of morphological features with findings by molecular genetics.

Theory of heterogeneous relaxation in compartmentalized tissues

A new model of compartmentalized relaxation--that which occurs for spins (protons) exchanging between compartments of different relaxation rates--is presented. This model generalizes previous ones by allowing spatially dependent relaxation within compartments. Solutions for the diffusion-Bloch equations are found via an efficient numerical technique known as the generalized moment expansion, and they agree well with the solutions to the standard two-site exchange equations (TSEE) for many typical situations. Specific models are developed for liposomes, red blood cells, capillaries, and arteries with respect to applied contrast agents. A parameter derived from tissue characteristics is introduced to predict the nature of the solutions. A new method is proposed for using contrast agents to detect capillaries, which exploits their high surface-to-volume ratio relative to the other elements of the vasculature.

Stromelysin-3 (ST-3) mRNA expression in colorectal carcinomas. Localization and clinicopathologic correlations

Stromelysin-3 (ST-3) mRNA expression was studied in 28 colorectal carcinomas and compared with that of adjacent nontumorous tissue. By Northern blot analysis, levels of ST-3 mRNA were significantly increased in the carcinomas compared with ST-3 expression was seen with degree of invasion, nodal or distant metastases, or histologic grade. In situ hybridization of nontumorous tissue showed no significant ST-3 expression. In tumor tissue, ST-3 mRNA was localized adjacent to colon carcinoma cells in irregular foci within the stoma. No significant difference in ST-3 expression was found between the center and periphery of the colon tumors. Most of the colon carcinomas (26 of 28) induced an expression of ST-3 in the directly adjacent stroma. No significant correlation between ST-3 mRNA expression and tumor stage and grade was seen. By Northern blot, we also saw expression of ST-3 in noncarcinomatous tissue, further supporting the concept that ST-3 expression is a tumor-induced but not a tumor-specific phenomenon.

Activation of human presupplementary motor area in learning of sequential procedures: a functional MRI study

1. Using functional magnetic resonance imaging, we investigated the neural correlates of sequential procedural learning. During the test scans the subjects learned a new sequence (position or color) of button presses; during the control scans they pressed the buttons in any order. The comparison of the test and control scans was expected to reveal the neural activities related to learning, not sensory-motor processes. 2. We found that a localized area in what we regard to be the human homologue of the presupplementary motor area (pre-SMA) was particularly active for learning of new sequential procedures (either position or color sequences), not movements per se. 3. In contrast, the SMA proper (posterior to pre-SMA) was active for the performance of sequential movements, not learning. This was shown in another paradigm in which the subjects pressed the buttons in any order in the test scans and just watched the sequence in the control scans. 4. The learning-related pre-SMA region, which was consistent across different experiments in single subjects, was identified on only one side in each subject.