Unsupervised learning of brain states from fMRI data.

The use of multivariate pattern recognition for the analysis of neural representations encoded in fMRI data has become a significant research topic, with wide applications in neuroscience and psychology. A popular approach is to learn a mapping from the data to the observed behavior. However, identifying the instantaneous cognitive state without reference to external conditions is a relatively unexplored problem and could provide important insights into mental processes. In this paper, we present preliminary but promising results from the application of an unsupervised learning technique to identify distinct brain states. The temporal ordering of the states were seen to be synchronized with the experimental conditions, while the spatial distribution of activity in a state conformed with the expected functional recruitment.

fMRI of triggerable aurae in musicogenic epilepsy.

The authors studied a patient with musicogenic epilepsy triggered by one specific musical piece using 3D PRESTO fMRI. During epileptic aurae initiated by the stimulus, signal increases were found in the left anterior temporal lobe, correlating with ictal EEG and SPECT showing a left anterior temporal focus, and the right gyrus rectus. Because fMRI indicated a cascade of recruitment of the ventral frontal lobes by epileptogenic music, left anterior temporal lobe activity could be secondary to a right gyrus rectus focus, possibly triggered by emotional processing of music.

Volumetric quantification of brain swelling after hypobaric hypoxia exposure.

We applied a novel MR imaging technique to investigate the effect of acute mountain sickness on cerebral tissue water. Nine volunteers were exposed to hypobaric hypoxia corresponding to 4572 m altitude for 32 h. Such an exposure may cause acute mountain sickness. We imaged the brains of the volunteers before and at 32 h of hypobaric exposure with two different MRI techniques with subsequent data processing. (1) Brain volumes were calculated from 3D MRI data sets by applying a computerized brain segmentation algorithm. For this specific purpose a novel adaptive 3D segmentation program was used with an automatic correction algorithm for RF field inhomogeneity. (2) T(2) decay rates were analyzed in the white matter. The results demonstrated that a significant brain swelling of 36.2 +/- 19.6 ml (2.77 +/- 1.47%, n = 9, P < 0.001) developed after the 32-h hypobaric hypoxia exposure with a maximal observed volume increase of 5.8% (71.3 ml). These volume changes were significant only for the gray matter structures in contrast to the unremarkable changes seen in the white matter. The same study repeated 3 weeks later in 6 of 9 original subjects demonstrated that the brains recovered and returned approximately to the initially determined sea-level brain volume while hypobaric hypoxia exposure once again led to a significant new brain swelling (24.1 +/- 12.1 ml, 1.92 +/- 0.96%, n = 6, P < 0.005). On the contrary, the T(2) mapping technique did not reveal any significant effect of hypobaria on white matter. We present here a technique which is able to detect reversible brain volume changes as they may occur in patients with diffuse brain edema or increased cerebral blood volume, and which may represent a useful noninvasive tool for future evaluations of antiedematous drugs.

Multisensory auditory-somatosensory interactions in early cortical processing revealed by high-density electrical mapping.

We investigated the time-course and scalp topography of multisensory interactions between simultaneous auditory and somatosensory stimulation in humans. Event-related potentials (ERPs) were recorded from 64 scalp electrodes while subjects were presented with auditory-alone stimulation (1000-Hz tones), somatosensory-alone stimulation (median nerve electrical pulses), and simultaneous auditory-somatosensory (AS) combined stimulation. Interaction effects were assessed by comparing the responses to combined stimulation with the algebraic sum of responses to the constituent auditory and somatosensory stimuli when they were presented alone. Spatiotemporal analysis of ERPs and scalp current density (SCD) topographies revealed AS interaction over the central/postcentral scalp which onset at approximately 50 ms post-stimulus presentation. Both the topography and timing of these interactions are consistent with multisensory integration early in the cortical processing hierarchy, in brain regions traditionally held to be unisensory.

Brain edema development after MRI-guided focused ultrasound treatment.

The aim of this study was to investigate a potential technique for image-guided minimally invasive neurosurgical interventions. Focused ultrasound (FUS) delivers thermal energy without an invasive probe, penetrating the dura mater, entering through the cerebrospinal fluid (CSF) space, or harming intervening brain tissue. We applied continuous on-line monitoring by MRI to demonstrate the effect of the thermal intervention on the brain tissue. For this, seven rabbits had a part of their skull removed to create access for the FUS beam into the brain through an acoustic window of 11 mm in diameter. Dura was left intact and skin was sutured. One week later, the rabbits were sonicated for 3 seconds with 21 W acoustic power, and the FUS focus was visualized with a temperature-sensitive T1-weighted MRI pulse sequence. The tissue reaction was documented over 7 days with T2-weighted images of the brain. The initial area of the central low signal intensity in the axial plane was .4+/-.3 mm2, and for the bright hyperintensity surrounding the lesion, it was 2.3+/-.6 mm2 (n = 7). In the coronal plane, the corresponding values were .4+/-.1 mm2 and 3.4+/-.9 mm2 (n = 5). The developing brain edema culminated 48 hours later and thereafter diminished during the next 5 days. Histology revealed a central necrosis in the white matter surrounded by edematous tissue with inflammatory cells. In summary, the image-guided thermal ablation technique described here produced a relatively small lesion in the white matter at the targeted location. This was accomplished without opening the dura or the need for a stereotactical device. MRI allowed on-line monitoring of the lesion setting and the deposition of thermal energy and demonstrated the tissue damage after the thermal injury.

The importance of arthroscopy in diagnosing synovial haemangioma of the knee joint.

In connection with one of their cases, authors call attention to the importance of differential diagnosis in synovial haemangioma of the knee joint, a rare condition. They also give a survey of its clinical, radiological and pathological features, review the literature on the topic, with special emphasis on the importance of arthroscopy in making the clinical diagnosis, and describe the treatment applied in their case.

Line scan diffusion imaging.

A novel line scan diffusion imaging sequence (LSDI) is introduced. LSDI is inherently insensitive to motion artifacts and high quality diffusion maps of the brain can be obtained rapidly without the use of head restraints or cardiac gating. Results from a stroke study and abdominal diffusion images are presented. The results indicate that it is feasible to use the LSDI technique for clinical evaluation of acute ischemic stroke. In contrast to echo-planar diffusion imaging, LSDI does not require modified gradient hardware and can be implemented on conventional scanners. Thus, LSDI should dramatically increase the general availability of robust clinical diffusion imaging.

Intracranial compartment volumes in patients with enlarged ventricles assessed by magnetic resonance-based image processing.

Magnetic resonance image-based computerized segmentation was used to measure the volumes of the brain, gray and white matter components, and to identify regions with prolonged enhancement on T2-weighted imaging, such as periventricular or deep white matter hyperintensities. The authors also determined the volumes of the ventricles and subarachnoid space in control subjects and in patients with: 1) aqueductal stenosis (AS); 2) other causes of obstructive hydrocephalus (OH); 3) Alzheimer's disease (AD); and 4) normal-pressure hydrocephalus (NPH). In AS the volume of the brain was smaller, whereas that of ventricles and subarachnoid cerebrospinal fluid space was larger than that of controls. The decrease in brain volume was due primarily to white matter loss. Although in OH the ventricles were larger, the subarachnoid space was smaller than in controls, presumably due to encroachment by the brain, in which the volume remained unchanged. In AD, loss of both gray and white matter resulted in a smaller brain volume, whereas that of ventricles and subarachnoid space was larger than in controls. In NPH patients, only ventricular volume was greater, whereas all other compartments were similar to controls. The brain normally occupies 87% to 92% of the intracranial volume and consequently, as observed in our patients, relatively small decrements in brain size lead to large increments in ventricular and/or extraventricular volumes. The magnitude of such changes differed markedly among our patient groups, and whether such changes prove useful in clinical assessment and differentiation needs to be determined.

Age-related changes in intracranial compartment volumes in normal adults assessed by magnetic resonance imaging.

Magnetic resonance (MR) image-based computerized segmentation was used to measure various intracranial compartments in 49 normal volunteers ranging in age from 24 to 80 years to determine age-related changes in brain, ventricular, and extraventricular cerebrospinal fluid (CSF) volumes. The total intracranial volume (sum of brain, ventricular, and extraventricular CSF) averaged 1469 +/- 102 cm3 in men and 1289 +/- 111 cm3 in women. The difference was attributable primarily to brain volume, which accounted for 88.6% of the respective intracranial volumes in both sexes, but was significantly larger in men (1302 +/- 112 cm3) than in women (1143 +/- 105 cm3). In both, the cranial CSF volume averaged 11.4%. Total intracranial volume did not change with age, although the normalized brain volume of both men and women began to decrease after the age of 40 years. This decrease was best reflected by expansion of the extraventricular CSF volume which, after the age of 50 years, was more marked in men than in women. The volume of the cranial CSF, as determined by MR image-based computerized segmentation, is considerably larger than traditionally accepted and resides mostly extraventricularly. Expansion of CSF volume with age provides a good index of brain shrinkage although evolving changes and growth of the head with age tend to confound the results.

Autocrine stimulation of a human lung mesothelioma cell line is mediated through the transforming growth factor alpha/epidermal growth factor receptor mitogenic pathway.

Malignant cells frequently acquire a certain independency of exogenous growth factors via the coexpression of epidermal growth factor receptor (EGFR) and epidermal growth factor (EGF)-related molecules. In the present study we investigate a possible involvement of EGF-related molecules in the growth of human lung mesothelioma. Four well-characterised cell lines are analysed for their responsiveness to exogenous EGF and transforming growth factor alpha (TGF-alpha) as well as for coexpression of EGFR and EGF/TGF-alpha. Both growth factors are able to stimulate DNA synthesis in three cell lines, although the degree of responsiveness is very variable, but neither EGF nor TGF-alpha has an effect on the cell line ZL34. In contrast, no heterogeneity is observed in the expression of EGFR, which is similarly high in all cell lines. Analysis of cell supernatants reveals that, whereas no EGF is detected, TGF-alpha is released by two cell lines. Furthermore, these two cell lines, ZL5 and ZL34, are shown to express the membrane anchored precursor pro-TGF-alpha. Thus, coexpression of EGFR and TGF-alpha is observed on two mesothelioma cell lines. The potential autocrine mitogenic role of TGF-alpha in these two cell lines was tested using neutralising antibodies against TGF-alpha and EGFR. In ZL5 cells DNA synthesis was not affected by the presence of neutralising antibodies, indicating that an external autocrine mitogenic pathway is not active in these cells. In ZL34 cells, however, the potential autocrine loop could be disrupted, as DNA synthesis was significantly reduced in the presence of neutralising antibodies. This result gives strong evidence for an autocrine role of TGF-alpha in the growth of the mesothelioma cell line ZL34.

[Ischemic cerebrovascular lesion caused by left atrial myxoma]. / Bal pitvari myxoma átal okozott ischaemiás cerebrovascularis laesio.

A case presentation is given of a 40 years old woman with acute ischemic cerebrovascular lesion in the territory of the left middle cerebral artery caused by embolization from a myxoma in the left atrium. The tumor was diagnosed by transthoracic echocardiography. Histological examination after cardiac surgery revealed a benignant myxoma. In the six-month-long postoperative follow up gradual improvement of the neurological signs was observed. The most important morphological and clinical characteristics of myxomas are summarized. The necessity of detailed cardiological examination of each young patient with stroke is emphasized.

In vitro effect of suramin on lung tumour cells.

In the search for new therapeutic concepts in lung cancer chemotherapy, suramin, a potential anticancer drug which evades multidrug resistance, was tested in vitro on 25 lung-derived cell lines, either non-tumorigenic cells, or established cell lines from five different tumour types. Suramin treatment resulted in a time- and dose-dependent decrease in [3H]thymidine incorporation, except in one adenocarcinoma cell line where DNA synthesis was highly stimulated. [3H]Leucine incorporation was less affected, indicating that suramin acted cytostatically rather than cytotoxically. Our results show that suramin affected DNA synthesis of the different types of lung derived cells, including non-tumorigenic and tumour cell lines, to a similar extent.

[Synovial chondromatosis of the knee joint]. / Térdízületi synovialis chondromatosis.

Authors removed more than hundred free bodies from the knee joint of a young female patient. In connection with their case the criteria of the synovial chondromatosis, the theories concerning the pathogenesis and the therapy to be chosen are described, based on literary data.

Surgical treatment of pathologic fractures from metastatic tumors of long bones.

Surgical treatment of 74 cases of impending and established metastatic pathologic fractures were analyzed. On the basis of various reports, the incidence of bone lesions, bone-seeking primary tumors, lesion sites, diagnostic techniques and possibilities, as well as indications for and methods of surgical treatment, are surveyed. Surgical intervention is only one aspect of the different components of general treatment in bone metastases. An aggressive surgical procedure yields very satisfactory results in most cases, compared with those of conservative treatment.

Morphological observations on the extracellular space in the macula densa of the mouse kidney.

Basolateral interstitial spaces (BLIS) of the murine macula densa (MD) are dilated in kidneys fixed either by in vivo glutaraldehyde perfusion or snap freezing-freeze substitution, suggesting that macula densa intercellular spaces may be normally dilated in the functioning nephron. BLIS are also dilated in MD with luminal obstruction with "hyaline" cylinder. This finding might indicate a glomerulo-macular fluid and solute streaming, having an impact on the tubuloglomerular feedback mechanism.

Morphological and immunohistochemical characteristics of dimethylnitrosamine-induced malignant mesenchymal renal tumor in F-344 rats.

Mesenchymal renal tumors in F-344 newborn rats were induced by a single dose of dimethylnitrosamine. The induced tumors were successfully transplanted into adult rats under the renal capsule. Neither the primary nor the transplanted neoplasms from various generations of grafts changed their morphological features during the tumor passage, having the same cellularity with high mitotic activity and the tendency to invade the host kidney rapidly. On the basis of lectin histochemistry and immunohistology, the tumor proved to be a mesenchymal neoplasm without any obvious capacity of the proliferating cells to differentiate into any well-known organoid element normally found in mature renal parenchyma. However, the proliferating neoplastic cells were found to have a strong vimentin positivity with desmin expression. Ultrastructurally, myofilaments with attachment bodies characteristic of smooth muscle cells were generally present in various amounts in many tumor cells. In addition, on the basis of the physiological data and on kidney/tumor renin activity obtained, it is interesting to note that the tumor-graft-invaded kidneys retained their enzyme activity, despite the obvious loss of renal tissue including glomeruli. However, the immunohistochemical findings with anti-renin antibody have clearly shown that this is not due to a renin-producing tumor but rather to the surviving (probably) non-neoplastic arterioles retaining the capacity to produce renin. Although these arterioles have mostly been found next to necrotic areas, commonly occurring in dimethylnitrosamine-induced transplantable renal tumors, the question of a possible physiological role of renin in tumor necrosis or in angiogenesis has remained open.

[Histologic study of periapical granulomas]. / Periapicalis granulomák szövettani vizsgálata.

Sixty-three periapical granulomas were histologically examined. They were divided into four types: exudative, granulomatous, granulofibrous and fibrous types. The most frequent forms were the granulomatous types. The granulomatous type consisted of four zones: necrotic, exudative, granulomatous and fibrous. In the granulomatous zone lymphocytes, plasma cells, macrophages, Russel bodies, foam cells, neutrophil leukocytes were found. Mast cells were found in the fibrous zone among the collagen fibres.