Simultaneous detection of valine and lactate using MEGA-PRESS editing in pyogenic brain abscess

Valine and lactate have been recognized as important metabolic markers to diagnose brain abscess by means of MRS. However, in vivo unambiguous detection and quantification is hampered by macromolecular contamination. In this work, MEGA-PRESS difference editing of valine and lactate is proposed. The method is validated in vitro and applied for quantitative in vivo experiments in one healthy subject and two brain abscess patients. It is demonstrated that with this technique the overlapping lipid signal can be reduced by more than an order of magnitude and thus the robustness of valine and lactate detection in vivo can be enhanced. Quantification of the two abscess MEGA-PRESS spectra yielded valine/lactate concentration ratios of 0.10 and 0.27. These ratios agreed with the concentration ratios determined from concomitantly acquired short-T_E PRESS data and were in line with literature values. The quantification accuracy of lactate (as measured with Cramér-Rao lower bounds in LCModel processing) was better for MEGA-PRESS than for short-T_E PRESS in all acquired in vivo datasets. The Cramér-Rao lower bounds of valine were only better for MEGA-PRESS in one of the two abscess cases, while in the other case coediting of isoleucine confounded the quantification in the MEGA-PRESS analysis. MEGA-PRESS and short-T_E PRESS should be combined for unambiguous quantification of amino acids in abscess measurements. Simultaneous valine/lactate MEGA-PRESS editing might benefit the distinction of brain abscesses from tumors, and further categorization of bacteria with reasonable sensitivity and specificity.

Correlation of DTI metrics in the wall and cavity of brain abscess with histology and immunohistochemistry

Diffusion tensor imaging (DTI) was performed in eight patients with brain abscess (BA). The aim of this study was to see the difference in the relationship between intercellular cell adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen-1 (LFA-1) expression and DTI metrics measured in vivo in the wall and cavity of BA and its possible explanation vis-à-vis histology and immunohistochemistry. Neuroinflammatory molecules (NMs) were quantified from BA cavity aspirate of the patients and quantitative immunohistochemical analysis was performed for ICAM-1 and LFA-1 in the BA wall, showing maximal positive staining and correlated with DTI metrics. The fractional anisotropy (FA) significantly increased while mean diffusivity and spherical anisotropy significantly decreased in the BA wall compared to the BA cavity. In the BA wall, FA and linear anisotropy (CL) showed a significant positive correlation with ICAM-1 and LFA-1 expression whereas FA and planar anisotropy positively correlated with NMs quantified from aspirated pus respectively. Higher FA values in the BA wall compared to BA cavity, even when ICAM-1 and LFA-1 were expressed only in the macrophages and not in the collagen fibers, suggests that a combination of both concentric layers of collagen fibers as well as neutrophils and macrophages provide structural orientation and are responsible for increased FA. In the BA wall, increased CL was found compared to the cavity, indicating the presence of concentrically laid collagen fibers responsible for the diffusion of water molecules in the direction parallel to the collagen fibers. We conclude that in the BA, different mechanisms are operative for the changes in the DTI metrics in the wall and cavity; these conclusions are validated by histology and immunohistochemistry.

Microbial genome dynamics in CNS pathogenesis

The balancing act between microbes and their host in commensal and disease states needs to be deciphered in order to fully treat and combat infectious diseases. The elucidation of microbial genome dynamics in each instance is therefore required. In this context, the major bacterial meningitis pathogens are Neisseria meningitidis, Haemophilus influenzae and Streptococcus pneumoniae. In prokaryotic CNS pathogenesis both the intact organism as well as its released components can elicit disease, often resulting in neurological sequelae, neurodegeneration or fatal outcome. The study of microbial virulence in CNS disease is expected to generate findings that yield new information on the general mechanisms of brain edema and excitatory neuronal disturbances due to meningitis, with significant potential for discoveries that can directly influence and inspire new strategies for prevention and treatment of this serious disease.

Modulation of connexin expression and gap junction communication in astrocytes by the gram-positive bacterium S. aureus

Gap junctions establish direct intercellular conduits between adjacent cells and are formed by the hexameric organization of protein subunits called connexins (Cx). It is unknown whether the proinflammatory milieu that ensues during CNS infection with S. aureus, one of the main etiologic agents of brain abscess in humans, is capable of eliciting regional changes in astrocyte homocellular gap junction communication (GJC) and, by extension, influencing neuron homeostasis at sites distant from the primary focus of infection. Here we investigated the effects of S. aureus and its cell wall product peptidoglycan (PGN) on Cx43, Cx30, and Cx26 expression, the main Cx isoforms found in astrocytes. Both bacterial stimuli led to a time-dependent decrease in Cx43 and Cx30 expression; however, Cx26 levels were elevated following bacterial exposure. Functional examination of dye coupling, as revealed by single-cell microinjections of Lucifer yellow, demonstrated that both S. aureus and PGN inhibited astrocyte GJC. Inhibition of protein synthesis with cyclohexamide (CHX) revealed that S. aureus directly modulates, in part, Cx43 and Cx30 expression, whereas Cx26 levels appear to be regulated by a factor(s) that requires de novo protein production; however, CHX did not alter the inhibitory effects of S. aureus on astrocyte GJC. The p38 MAPK inhibitor SB202190 was capable of partially restoring the S. aureus-mediated decrease in astrocyte GJC to that of unstimulated cells, suggesting the involvement of p38 MAPK-dependent pathway(s). These findings could have important implications for limiting the long-term detrimental effects of abscess formation in the brain which may include seizures and cognitive deficits.

Voriconazole brain tissue levels in rhinocerebral aspergillosis in a successfully treated young woman

Invasive aspergillosis of the central nervous system has a mortality rate exceeding 90%. We describe a 29-year-old woman with a medical history of chronic polyarthritis who developed a proven rhinocerebral Aspergillus fumigatus infection refractory to first-line treatment with liposomal amphotericin B. The patient responded successfully to salvage combination treatment with voriconazole and caspofungin. Furthermore, for the first time, voriconazole levels in an intracerebral abscess were measured in this patient undergoing voriconazole oral therapy.

Nestin expression in reactive astrocytes of human pathology

There is a general agreement on the Nestin re-expression in reactive astrocytes, but its modalities differ among experimental animal species and between the latter and human material. In a series of 40 surgical specimens, including gliomas, vascular malformations, abscesses and angiomas, the glial reaction has been studied by immunohistochemistry and immunofluorescence of Nestin, GFAP and Vimentin. The observations made by immunohistochemistry were comparable with those by immunofluorescence. In some lesions, glial reaction was long-lasting and astrocytes were in the same late maturation stage. In other lesions, such as invading malignant gliomas, astrocytes occurred in different maturation stages. In comparison with GFAP, Nestin was poorly expressed in mature astrocytes and more expressed in developing reactive astrocytes, mainly in the cytoplasms, with a great variability, and much less in the processes. In the invading tumor, developing positive astrocytes were hardly distinguishable from tumor invading astrocytes that, interestingly, were much more Nestin- than GFAP-positive. In the deep tumor reactive astrocytes were no more visible. The interpretation of the findings was based on what is known on the reciprocal behavior of the three antigens in maturing astrocytes during embryogenesis and on the hypothesis of an embryonic regression of reactive astrocytes. The impossibility to distinguish them from tumor cells in the deep tumor legitimates the suspicion of their recruitment among tumor cells.

Regulation of the inflammatory response to Staphylococcus aureus-induced brain abscess by interleukin-10

A characteristic of brain abscess is a localized suppurative infection leading to substantial damage of the adjacent central nervous system tissue. The orchestrated interplay of pro- and antiinflammatory cytokines released by leukocytes as well as resident cells of the central nervous system is crucial for both an effective host defense and for limiting tissue damage in brain abscess. To study the regulatory role of interleukin (IL)-10 in brain abscess in vivo, IL-10-deficient (IL-10(0/0)) mice were stereotaxically infected with Staphylococcus aureus-laden agarose beads. Increased numbers of intracerebral (IC) granulocytes, macrophages, CD4+ and CD8+ T cells, and higher levels of TNF, IL-1beta, and iNOS were observed in IL-10(0/0) mice than in wild-type mice, whereas chemokines were induced earlier and more pronounced in wild-type mice. Together with prominent microvascular hemorrhage, necrotic vasculitis, severe brain edema, and markedly increased abscess size, these alterations led to an increased morbidity of IL-10(0/0) mice. Nevertheless, the hyperinflammatory response of IL-10(0/0) mice did not improve bacterial elimination. Collectively, these data outline the important role of IL-10 in vivo for the regulation of the IC host immune response in experimental S. aureus-induced brain abscess.

Aggressive G-CSF-producing gastric cancer complicated by lung and brain abscesses, mimicking metastases

A 57-year-old Japanese man had type II c gastric cancer with marked lymph node metastases associated with leukocytosis and elevated granulocyte colony-stimulating factor (G-CSF). Total gastrectomy and distal pancreatectomy with lymph node dissection were performed. Although the primary lesion was negative for G-CSF by histopathological immunostaining, a highly increased G-CSF m-RNA level, measured using reverse transcriptase-polymerase chain reaction in frozen sections, led to a diagnosis of G-CSF-producing gastric cancer. The leukocytes and G-CSF decreased immediately after surgery. He then had an intraabdominal recurrence, and was diagnosed with multiple tumors in his lung and brain, with abnormally elevated leukocytes and greatly increased G-CSF; he died 4 months after the surgery. Autopsy showed intraabdominal recurrence of cancer, with no metastases to the lung or brain, but with multiple brain and lung abscesses. We speculate that the excessively increased neutrophils induced by G-CSF infiltrated the lung and brain and formed abscesses, mimicking metastases.

Aquaporin-4 gene deletion in mice increases focal edema associated with staphylococcal brain abscess

Brain abscess is associated with local vasogenic edema, which leads to increased intracranial pressure and significant morbidity. Aquaporin-4 (AQP4) is a water channel expressed in astroglia at the blood-brain and brain-CSF barriers. To investigate the role of AQP4 in brain abscess-associated edema, live Staphylococcus aureus (10(5) colony-forming units) was injected into the striatum to create a focal abscess. Wild-type and AQP4-deficient mice had comparable immune responses as measured by brain abscess volume (approximately 3.7 mm3 at 3 days), bacterial count and cytokine levels in brain homogenates. Blood-brain barrier permeability was increased comparably in both groups as assessed by extravasation of Evans blue dye. However, at 3 days the AQP4 null mice had significantly higher intracranial pressure (mean +/- SEM 27 +/- 2 vs. 17 +/- 2 mmHg; p < 0.001) and brain water content (81.0 +/- 0.3 vs. 79.3 +/- 0.5 % water by weight in the abscess-containing hemisphere; p < 0.01) than wild-type mice. Reactive astrogliosis was found throughout the abscess-containing hemisphere; however, only a subset of astrocytes in the peri-abscess region of wild-type mice had increased AQP4 immunoreactivity. Our findings demonstrate a protective effect of AQP4 on brain swelling in bacterial abscess, suggesting that AQP4 induction may reduce vasogenic edema associated with cerebral infection.

Pyogenic brain abscess: findings from in vivo 1.5-T and 11.7-T in vitro proton MR spectroscopy

BACKGROUND AND PURPOSE

Metabolites in pyogenic brain abscesses, as detected with in vivo proton MR spectroscopy, are different from those found in brain and can help differentiate pyogenic brain abscesses from necrotic neoplasms. We compared the findings of in vivo with those of in vitro MR spectroscopy and categorized the MR spectral patterns with respect to the causative organisms and abscess size.

METHODS

Fifteen patients with pyogenic brain abscesses underwent in vivo 1.5-T (1)H MR spectroscopy and had findings of ring enhancement. The causative organisms were determined from cultures of aspirated pus. Single-voxel (1)H MR spectroscopy was performed with the point-resolved method (1600/270, 135 TR/TE). In six representative patients, in vitro 11.7-T (1)H MR spectra were obtained from the aspirated pus.

RESULTS

Three in vivo MR spectral patterns were noted: A) presence of lactate at 1.3 ppm, cytosolic amino acids (leucine, isoleucine, and valine) at 0.9 ppm, alanine at 1.50 ppm, and acetate at 1.92 ppm, with the presence or absence of succinate at 2.4 ppm and lipids (0.8-1.3 ppm), representing mostly obligate anaerobes or a mixture of obligate and facultative anaerobes; B) presence of lactate at 1.3 ppm and cytosolic amino acids at 0.9 ppm, with the presence or absence of lipids but not acetate or alanine (0.8-1.3 ppm), representing mostly obligate aerobes or facultative anaerobes; and C) presence of lactate at 1.3 ppm alone, showing small abscess. Additional resonance peaks of lysine at 1.73 and 3.0 ppm, glutamate/glutamine at 2.09-2.36 ppm, taurine at 3.24 and 3.42 ppm, glycine at 3.55 ppm, and amino acids at 3.75 ppm could be observed in the in vitro MR spectra.

CONCLUSION

Results from the in vivo observations were satisfactorily verified by the in vitro experiments. The in vitro measurements may offer complementary information that cannot be extracted from in vivo MR spectra. Determination of the three (1)H MR spectral patterns may be helpful in devising the best possible treatment plans for patients with pyogenic abscesses.

Biological correlates of diffusivity in brain abscess

Restricted diffusion in brain abscess is assumed to be due to a combination of inflammatory cells, necrotic debris, viscosity, and macromolecules present in the pus. We performed diffusion-weighted imaging (DWI) on 41 patients with proven brain abscesses (36 pyogenic and five tuberculous), and correlated the apparent diffusion coefficient (ADC) from the abscess cavity with viable cell density, viscosity, and extracellular-protein content quantified from the pus. On the basis of the correlation between cell density and ADC in animal tumor models and human tumors in the literature, we assumed that the restricted ADC represents the cellular portion in the abscess cavity. We calculated restricted and unrestricted lesion volumes, and modeled cell density over the restricted area with viable cell density per mm(3) obtained from the pus. The mean restricted ADC in the cavity (0.65 +/- 0.01 x 10(-3) mm(2)/s) correlated inversely with restricted cell density in both the pyogenic (r = -0.90, P = <0.05) and tuberculous (0.60 +/- 0.04 x 10(-3) mm(2)/s, r = -0.94, P = <0.05) abscesses. We conclude that viable cell density is the main biological parameter responsible for restricted diffusion in brain abscess, and it is not influenced by the etiological agents responsible for its causation.

The neuropathology of melioidosis: two cases and a review of the literature

Melioidosis is an infectious disease caused by Burkholderia pseudomallei and is hyperendemic in the Top End of the Northern Territory of Australia, as well as being widespread throughout tropical south east Asia. The infection is primarily acquired via the inoculation of compromised surface tissues by contaminated soils and water and it can cause an acute, rapidly fatal illness. Although pneumonia is the commonest manifestation, neurological presentations have been described, most notably encephalomyelitis. This paper presents the neuropathology of 2 fatal cases of neurological melioidosis and reviews the relevant literature.

Diffusion-weighted imaging in the assessment of brain abscesses therapy

BACKGROUND AND PURPOSE

Surgically or conservatively treated brain abscesses may resolve, or pus may re-accumulate, requiring further intervention or treatment change. We hypothesized that diffusion-weighted (DW) imaging is useful in depicting features of abscesses related to therapeutic success or failure.

METHODS

Conventional contrast-enhanced T1- and T2-weighted imaging and DW imaging were performed in seven patients (aged 30-69 years) with proved pyogenic brain abscesses. The center of the abscess was qualitatively and quantitatively analyzed at initial and follow-up imaging in all patients. We correlated the signal intensity on trace DW images and the apparent diffusion coefficients (ADCs) with the clinical and laboratory data, particularly with respect to treatment failure and repeat therapy.

RESULTS

Surgical drainage was performed in six patients; one patient was treated with only antibiotics. All abscess cavities initially had high signal intensity (restricted diffusion) on DW images, with a mean ADC value of 0.52 x 10 (-3)mm (2)/s. Low signal intensity at DW imaging with high ADC were seen on follow-up images in the patient receiving medication and in four patients in whom the abscesses were drained; this correlated with a good therapeutic response. Two patients underwent drainage; their second follow-up DW images showed areas of high signal intensity and low ADC values suggesting re-accumulation of pus. Increased C-reactive protein level and WBC count correlated well with DW image findings.

CONCLUSION

DW imaging was superior to conventional MR imaging in evaluating the success or failure of abscess therapy. Restricted diffusion in a drained abscess corresponded to pus.

Assignment of the 2.03 ppm resonance in in vivo 1H MRS of human brain tumour cystic fluid: contribution of macromolecules

MRI and MRS are established techniques for the evaluation of intracranial mass lesions and cysts. The 2.03 ppm signal recorded in their (1)H-MRS spectra is often assigned to NAA from outer volume contamination, although it has also been detected in non-infiltrating tumours and large cysts. We have investigated the molecular origin of this resonance in ten samples of cystic fluids from human brain tumours. The NMR detected content of the 2.03 ppm resonance in 136 ms echo time spectra, assuming an N- CH(3) origin, was 3.19 +/- 1.01 mM. Only one third (34 +/- 12%) of the N-acetyl containing compound (NAC) signal could be extracted by perchloric acid (PCA) indicating that most of it originated in a macromolecular PCA-insoluble component. Chemical analysis of the cyst fluids showed that sialic acid bound to macromolecules would account for 64.3% and hexuronic containing compounds for 29.2% of the NMR-detectable ex vivo signal, 93.4% of the signal at TE 136 ms. Lactate content measured by NMR (6.4 +/- 4.4 mM) and the predominance of NAC originating in sialic acid point to a major origin from tumour rather than from plasma for this 2.03 ppm resonance.

The intermediate filament GFAP is important for the control of experimental murine Staphylococcus aureus-induced brain abscess and Toxoplasma encephalitis

The functional role of astrocytes exerted via their intermediate protein glial fibrillary acidic protein (GFAP) in CNS infections was studied in Staphylococcus aureus-induced brain abscess. Compared to wild type (WT) mice, GFAP(0/0) mice developed larger and more poorly demarcated inflammatory lesions paralleled by a significantly increased intracerebral bacterial load, a diffuse leukocytic infiltration of the contralateral hemisphere, purulent ventriculitis, vasculitis, and severe brain edema. These observations were correlated with the lack of a bordering function of activated astrocytes that strongly upregulated their GFAP expression in the abscess surrounding of WT mice. Clinically important, this lack of restriction of inflammation markedly aggravated the course of disease with manifestation of seizures and a severe weight loss in GFAP(0/0) mice. These data were paralleled by observations in the model of Toxoplasma encephalitis (TE) during which the intracerebral parasitic load was significantly increased. Moreover, tachyzoite-induced tissue necrosis was exclusively found in the brains of GFAP(0/0) mice in chronic TE. Collectively, these findings delineate a host defense function of astrocytes via restricting pathogenic spread and multiplication within the CNS, thereby contributing to the protection of the highly vulnerable brain parenchyma.

Pituitary abscess showing high uptake of thallium-201 on single photon emission computed tomography--case report

A 32-year-old female presented with a rare case of pituitary abscess manifesting as homonymous hemianopsia. Serum prolactin level was slightly high (40.8 ng/ml). Magnetic resonance (MR) imaging showed the content of the lesion as homogeneously isointense on the T1-weighted images and hyperintense on the T2-weighted images. The capsule of the lesion, which appeared thin and smooth, was enhanced by gadolinium. Dural enhancement around the sella turcica was also recognized. Thallium-201 single photon emission computed tomography (201Tl SPECT) showed homogeneous high accumulation in the pituitary region on both the early and delayed images. The lesion was treated via a transnasaltranssphenoidal approach. The cystic lesion contained pus and the capsule consisted of normal pituitary gland with inflammatory changes. The patient was treated with antibiotics for 3 weeks and the pituitary abscess was cured completely. Pituitary abscess can be differentiated from pituitary adenoma as lesion with a homogeneous high uptake on 201Tl SPECT on both the early and delayed images, and no enhancement of the central portion on MR images.

[Contribution of magnetic resonance spectrometry to the diagnosis of intracranial tumors]

Magnetic resonance spectroscopy (MRS) is a method enabling the analysis of the tissue metabolic content. It may offer a more accurate diagnosis of the intracranial tumors than conventional MRI sequences. MRS of normal brain parenchyma displays 4 main metabolites: N-acetyl aspartate (neuronal marker), creatine (cellular density marker), choline (membrane activity marker) and myoinositol (glial marker); pathological processes lead to variations of the level of these metabolites and/or the appearance of abnormal metabolites (lactate), following different patterns according to pathological process involved: glioma, meningioma, metastasis, bacterial or toxoplasmic abscess, radionecrosis. The potential clinical use of this method includes positive, differential and etiological diagnosis of tumors, determination of the level of malignancy of gliomas, screening for tumor recurrence following treatment. Our laboratory has been performing MR spectroscopic explorations of brain tumors for many years. Based on this experience, we show how MRS can be routinely performed in the clinical setting, what are its limitations and potential, and what kind of information can be supplied to the clinician.

Nestin and small heat shock protein expression on reactive astrocytes and endothelial cells in cerebral abscess

Cerebral abscess results in an extensive capsular formation, which is an important limiting barrier for the spread of microorganism. Reactive astrocytes and endothelial cells are major cellular components of the abscess capsule together with fibrocytes. Molecular pathogenesis that results in the migration and proliferation of these cells remain speculative. Intermediate filament (IF) nestin and small heat shock proteins (sHSP) are developmentally regulated protein. In this study, we found that nestin expression is re-induced in not only reactive astrocytes, but also in endothelial cells in the gliotic area of the capsule. These nestin expressing astrocytes and endothelial cells also expressed sHSPs, such as heat shock protein 27 (HSP27) and alphaB-crystalline. These results indicated that embryonic reversions of cytoskeletal proteins to nestin and the increased expression of sHSPs in in reactive astrocytes and endothelial cells are caused by pathogenic microorganism induced inflammatory stress.

Thallium-201 accumulation in a patient with brain abscess

A 57-year-old man was admitted to our hospital because of high fever and generalized tonic seizure. Brain magnetic resonance imaging (MRI) delineated multiple abnormal intensity areas. Thallium-201 (201Tl) scintigraphy revealed abnormal uptake in the brain. The imaging findings did not allow definitive exclusion of brain tumor, even though brain abscess was the more strongly suspected diagnosis. As the patient improved, the multiple abnormal intensity areas in the brain on MRI and the abnormal areas of accumulation on 201Tl scintigraphy were reduced, and eventually completely disappeared. A final diagnosis of brain abscess was therefore made. Since relatively few studies have reported 201Tl accumulation in cases of brain abscess, we report here our patient in whom the changes in the accumulation of 201Tl in a brain abscess were observed over time.

Chronological change of brain abscess in (1)H magnetic resonance spectroscopy

We studied chronological magnetic resonance spectral changes in brain abscesses before and after medical and/or surgical treatment. We examined five patients with MRI imaging and (1)H magnetic resonance spectroscopy (MRS) on two or more occasions, using two volume-of-interest patterns, and saw chronological changes related to the evolution of the abscess. A spectrum specific for brain abscess was found in three of the five cases, while two showed a single lactate peak in the first study. In two cases, phenylalanine or alanine appeared in the second study. We observed the disappearance of the specific spectra and a single lactate peak following surgery. Only one patient showed different spectra in different volume of interest.

Clinical application of proton magnetic resonance spectroscopy in the diagnosis of intracranial mass lesions

Diagnosis of primary and secondary brain tumours and other focal intracranial mass lesions based on imaging procedures alone is still a challenging problem. Proton magnetic resonance spectroscopy (1H-MRS) gives completely different information related to cell membrane proliferation, neuronal damage, energy metabolism and necrotic transformation of brain or tumour tissues. Our purpose was to evaluate the clinical utility of 1H-MRS added to MRI for the differentiation of intracranial neoplastic and non-neoplastic mass lesions. 176 mostly histologically verified lesions were studied with a constant clinically available single volume 1H-MRS protocol following routine MRI. 12 spectra (6.8%) were not of satisfactory diagnostic quality; 164 spectroscopic data sets were therefore available for definitive evaluation. Our study shows that spectroscopy added to MRI helps in tissue characterization of intracranial mass lesions, thereby leading to an improved diagnosis of focal brain disease. Non-neoplastic lesions such as cerebral infarctions and brain abscesses are marked by decreases in choline (Cho), creatine (Cr) and N-acetyl-aspartate (NAA), while tumours generally have elevated Cho and decreased levels of Cr and NAA. Gliomas exhibit significantly increased Cho and lipid formation with higher WHO tumour grading. Metastases have elevated Cho similar to anaplastic astrocytomas, but can be differentiated from high-grade gliomas by their higher lipid levels. Extra-axial tumours, i.e. meningiomas and neurinomas, are characterized by a nearly complete absence of the neuronal marker NAA. The additive information of 1H-MRS led to a 15.4%-higher number of correct diagnoses, to 6.2% fewer incorrect and 16% fewer equivocal diagnoses than with structural MRI data alone.

In vivo single-voxel proton MR spectroscopy in brain lesions with ring-like enhancement

It is often difficult to make a correct diagnosis of ring-like enhanced lesions on Gd-enhanced MR brain images. To differentiate these lesions using proton MR spectroscopy (1H-MRS), we retrospectively evaluated the correlation between the 1H-MR spectra and histopathological findings. We evaluated proton MR spectra obtained from the lesions in 45 patients, including metastasis (n = 19), glioblastoma (n = 10), radiation necrosis (n = 7), brain abscess (n = 5), and cerebral infarction (n = 4). The rate of misdiagnosis was found to be lowest at the threshold level of 2.48 for the (choline containing compounds)/(creatine and phosphocreatine) ratio (Cho/Cr) obtained from the whole lesions, which include the enhanced rim and the non-enhanced inner region. That is, the positively predictive values of a Cho/Cr greater than 2.48 for diagnosing metastasis or glioblastoma was 88.9 and 60.0%, respectively, and the positively predictive value of a Cho/Cr less than 2.48 for diagnosing radiation necrosis or cerebral infarction was 71.4 and 100%, respectively. For further differentiating between metastasis and glioblastoma, information about the presence and absence of an N-acetyl-aspartate (NAA) peak and lipid- or lactate-dominant peak was found to be useful. In 73.7% of metastasis cases a lipid-dominant peak was observed in the whole lesion without an NAA peak in the inner region, whereas the same pattern was observed in only 10% of the glioblastoma cases. Correlation with the histopathological findings showed that a high Cho signal is suggestive of neoplasm. Lipid signal in the non-enhanced central region was correlated to necrosis. Lactate signals were often observed in glioblastoma, abscess and sometimes metastasis, presumably reflecting the anaerobic glycolysis by the living cells in the ring-like enhanced rim. Single-voxel proton MR spectroscopy may serve as a potential tool to provide useful information of differentiation of ring-like enhanced lesions that cannot be diagnosed correctly using enhanced MR images alone.

Differentiation of tuberculous from pyogenic brain abscesses with in vivo proton MR spectroscopy and magnetization transfer MR imaging

BACKGROUND AND PURPOSE

MR imaging features are nonspecific with respect to the causative organism for patients with brain abscesses. On the basis of the hypothesis that the biochemical environment depends on the infecting organism and might be different in tuberculous compared with pyogenic brain abscesses, this study attempted to determine whether pyogenic brain abscesses can be differentiated from tuberculous brain abscesses by use of magnetization transfer (MT) MR imaging and in vivo proton MR spectroscopy.

METHODS

Twenty-seven patients with a total of 33 pyogenic brain abscesses and three patients with a total of 12 tuberculous abscesses were evaluated with in vivo MR spectroscopy and MT MR imaging. The diagnosis in all cases was based on the culture of the causative organisms and histopathology whenever done as a part of clinical management.

RESULTS

All 27 patients with pyogenic brain abscesses had lipid and lactate levels of 1.3 ppm and amino acid levels of 0.9 ppm with or without the presence of succinate, acetate, alanine, and glycine, while the three patients with tuberculous abscesses showed only such lipid and lactate levels. The MT ratio from the wall of the pyogenic abscesses was significantly higher (P <.001) than that from the tuberculous abscess wall.

CONCLUSION

It might be possible to differentiate tuberculous abscesses from pyogenic abscesses by using MT MR imaging and in vivo MR spectroscopy, which could be of value in influencing the management of such cases.

[Aspiration and drainage for a gas-producing brain abscess causing delayed bleeding from the abscess capsule--a case report]

A 65-year-old man was admitted with the complaint of gait disturbance. CT scan revealed a low density lesion in the right parietal lobe. MRI was carried out 3 days after admission, the lesion showing low intensity on T1 WI and T2 WI. Gd-DTPA enhanced T1 WI showing abnormal enhancement surround it. CT scan then revealed a gas bubble in the lesion 12 days after admission, so we diagnosed it as gas-producing brain abscess and aspiration, drainage and irrigation with antibiotics were performed. Although, the brain abscess was reduced in size after the operation, the lesion expanded again 2 weeks after the operation. MRI was performed and the lesion showed iso-intensity on T1 WI and high intensity on T2 WI. Emergent aspiration and drainage were performed and uncoagulated old-hematoma-like matter such as chronic subdural hematoma was removed. As significant neovascularization with inflammatory cells had been detected in the capsule of the brain abscess, we suspected that aspiration and drainage surgery for brain abscess may cause delayed bleeding from the capsule of the abscess. We conclude that attention should be drawn to such a complication.

Discrimination of Brin Abscess and Cystic Tumor by In Vivo Proton Magnetic Resonance Spectroscopy

Proton magnetic resonance (MR) spectroscopy was evaluated for the differentiation of brain abscesses and cystic brain tumors. Proton MR spectroscopy was performed in vivo in two patients with brain abscess and eight patients with various cystic brain tumors (anaplastic astrocytoma, glioblastoma, and metastatic brain tumor). MR imaging with contrast medium demonstrated ring-like enhanced mass lesions in all patients. The various resonance peaks in proton MR spectra were assigned to metabolites according to chemical shifts. Treatment of the cystic brain lesions was based on the information from proton MR spectroscopy. Aspirated pus from one patient with brain abscess was examined using ex vivo proton MR spectroscopy. The in vivo spectra of brain abscess contained resonance peaks attributed to acetate, lactate, alanine, amino acids, and lipids in both cases, and an additional peak of succinate in one case. In vivo spectra of the neoplasms contained resonance peaks corresponding to lactate, lipids, choline, creatine, and N-acetyl aspartate. Proton MR spectroscopy is useful for discriminating brain abscess from cystic tumors with similar neuroimaging appearance, which is very important for determining the treatment strategy.

Proinflammatory cytokine, chemokine, and cellular adhesion molecule expression during the acute phase of experimental brain abscess development

Brain abscess represents the infectious disease sequelae associated with the influx of inflammatory cells and activation of resident parenchymal cells in the central nervous system. However, the immune response leading to the establishment of a brain abscess remains poorly defined. In this study, we have characterized cytokine and chemokine expression in an experimental brain abscess model in the rat during the acute stage of abscess development. RNase protection assay revealed the induction of the proinflammatory cytokines interleukin (IL)-1alpha, IL-1beta, IL-6, and tumor necrosis factor-alpha as early as 1 to 6 hours after Staphylococcus aureus exposure. Evaluation of chemokine expression by reverse transcription-polymerase chain reaction demonstrated enhanced levels of the CXC chemokine KC 24 hours after bacterial exposure, which correlated with the appearance of neutrophils in the abscess. In addition, two CC chemokines, monocyte chemoattractant protein-1 and macrophage inflammatory protein-1alpha were induced within 24 hours after S. aureus exposure and preceded the influx of macrophages and lymphocytes into the brain. Analysis of abscess lesions by in situ hybridization identified CD11b+ cells as the source of IL-1beta in response to S. aureus. Both intercellular adhesion molecule-1 and platelet endothelial cell adhesion molecule expression were enhanced on microvessels in S. aureus but not sterile bead-implanted tissues at 24 and 48 hours after treatment. These results characterize proinflammatory cytokine and chemokine expression during the early response to S. aureus in the brain and provide the foundation to assess the functional significance of these mediators in brain abscess pathogenesis.

Quantitative proton magnetic resonance spectroscopy of focal brain lesions

The diagnostic value of single-voxel proton magnetic resonance spectroscopy (2 T, stimulated echo acquisition mode, TR = 6,000 ms, TE = 20 ms, 4-5 mL volumes-of-interest) was assessed for a differentiation of focal brain lesions of unknown etiology in 17 patients 1-14 years of age. Absolute metabolite concentrations were compared with age-matched control subjects and an individual control region. Most of the brain tumors were characterized by strongly reduced total N-acetylaspartyl compounds and marked increases of myo-inositol and choline-containing compounds, consistent with a lack of neuroaxonal tissue and a proliferation of glial cells. Lactate was elevated in only four patients. When using this pattern for a metabolic discrimination of brain tumors from other focal lesions, proton spectroscopy correctly identified 14 of 17 abnormalities, as confirmed by histologic examination after neurosurgical intervention. One false-positive tumor diagnosis was a severe reactive gliosis mimicking a typical tumor spectrum. Two inconclusive cases comprised an astrocytoma with moderately elevated myo-inositol but reduced choline-containing compounds and a patient with an abscess leading to a marked reduction of all metabolites but strong contributions from mobile lipids. In summary, quantitative proton spectroscopy has considerable clinical value for preoperative characterization of focal brain lesions.

Reversible alterations in brain metabolites during therapy for disseminated nocardiosis using proton magnetic resonance spectroscopy

We report reversible abnormalities in magnetic resonance spectra acquired from a patient with AIDS undergoing antibiotic and corticosteroid therapy for disseminated nocardiosis, a rare opportunistic infection of immunosuppressed patients which can cause cerebral abscess formation. There was no clinical, CT or MRI evidence of HIV-1 encephalitis. MR spectra were acquired before and after treatment using a two-dimensional chemical shift imaging technique (TR 1500ms, TE 130ms). Prior to treatment, a rise in the choline to creatine ratio and a reduction in the N-acetylaspartate to creatine ratio were observed in MR spectra localized to areas of the left anteromedial centrum semiovale that appeared normal on MR imaging. After 16 weeks, the patient had recovered with complete resolution of the cerebral abscesses on MRI. The MR spectral abnormalities also returned to normal. Two months later, the patient had a relapse with focal neurological signs and further abscesses were demonstrated on MRI of the brain. The patient subsequently died and histopathological and microbiological findings at autopsy confirmed the clinical picture of a recurrence of cerebral nocardiosis with no evidence of HIV-1 encephalitis. This case illustrates reversible MR-measurable metabolite changes in the brain of an HIV-seropositive patient without HIV-1 encephalitis who underwent treatment for cerebral nocardiosis.

Diagnostic assessment of brain tumours and non-neoplastic brain disorders in vivo using proton nuclear magnetic resonance spectroscopy and artificial neural networks

PURPOSE

Experiments were carried out to assess the potential of artificial neural network (ANN) analysis in the differential diagnosis of brain tumours (low- and high-grade gliomas) from non-neoplastic focal brain lesions (tuberculomas and abscesses), using proton magnetic resonance spectroscopy (1H MRS) as input data.

METHODS

Single-voxel stimulated echo acquisition mode (STEAM) (echo time of 20 ms) spectra were acquired from 138 subjects including 15 with low-grade gliomas, 47 with high-grade gliomas, 18 with tuberculomas, 18 with abscesses and 40 healthy controls. Two neural networks were constructed using the spectral points from 0.6 to 3.4 parts per million. In the first network construction, the ANN had to differentiate between tumours from infections, while the second network had to differentiate between all five histological classes.

RESULTS

ANN analysis gave a histologically correct diagnosis for low- and high-grade gliomas with an accuracy of 73% and 98% respectively. None of the 62 tumours was diagnosed as an infectious lesion. Among the non-neoplastic lesions, ANN classification was correct in 89% of tuberculomas and in 83% of brain abscesses. The specificity of ANN diagnosis was 98%, 92%, 99%, and 100% for low-grade gliomas, high-grade gliomas, tuberculomas and abscesses respectively.

CONCLUSION

The present data show the clinical utility of non-invasive 1H MRS by automated ANN analysis in the diagnosis of tumour and non-tumour cerebral disorders.

In vivo proton MR spectroscopy of untreated and treated brain abscesses

MR spectroscopy was performed in three patients with brain abscesses. In two patients, MR spectroscopy revealed end-products of bacterial breakdown (acetate, succinate, amino acids, lactate) in the abscess cysts. In one of these, the spectrum was reversed to a single lactate peak after treatment. In the third patient, MR spectroscopy was performed only after treatment and showed a single nonspecific lactate peak. MR spectroscopy is a potential tool for noninvasive diagnosis of brain abscess and might be useful for evaluating changes after treatment.

In vivo single-voxel proton MR spectroscopy in intracranial cystic masses

PURPOSE

Our objective was to evaluate the proton MR spectroscopic pattern of the cystic contents of various intracranial masses and to report characteristic spectral patterns that may be helpful in the differential diagnosis of these lesions.

METHODS

We evaluated 40 proton MR spectra obtained from cystic contents of various intracranial cystic masses in 39 patients, including gliomas (n = 14), metastases (n = 3), abscesses (n = 8), cysticercosis (n = 4), epidermoids (n = 3), and others (n = 7). Proton MR spectroscopy was performed on a 1.5-T MR unit using a point-resolved spectroscopic sequence with a 2 x 2 x 2 cm3 volume of interest. Assignment of the resonance peaks was based on previous studies.

RESULTS

Adequate proton MR spectroscopic data were obtained in 35 cases (88%). In most gliomas and metastases, only a lactate resonance was observed. There was a trend toward a higher lactate peak in high-grade gliomas. A few tumors, including malignant gliomas and metastases, showed lipid signal combined with lactate signal. In abscesses, there were various combinations of lactate, acetate, succinate, amino acids (including valine, alanine, and/or leucine), and/or unassigned resonances. In cysticercosis, resonances of lactate, succinate, alanine, acetate, and/or unassigned resonances were observed. Three epidermoid cysts showed only lactate signal. There were no identifiable resonances from the arachnoid and porencephalic cysts.

CONCLUSION

Only lactate is commonly observed in a variety of intracranial cystic masses, except for abscess and cysticercosis, in which resonances of acetate, succinate, amino acids, and/or unassigned metabolites can be seen in addition to a lactate peak.

Role of in vivo proton magnetic resonance spectroscopy in the diagnosis and management of brain abscesses

OBJECTIVE

In vivo proton magnetic resonance spectroscopy was performed for 24 patients with pyogenic brain abscesses, to examine the consistency of the spectral patterns and to observe the changes in metabolites with treatment.

METHODS

Localized proton spectra were obtained from 4- to 8-ml volumes in the abscesses, using stimulated echo acquisition mode and spin echo sequences. Twenty-two patients were treated with combined surgical and medical therapy, and two patients were treated conservatively. High-resolution magnetic resonance spectroscopy was performed for 15 samples of abscesses obtained from these patients, to confirm the assignments of resonances seen in vivo. Postaspiration studies were performed for 12 patients treated with combined medical and surgical therapy and 2 patients treated medically.

RESULTS

Lactate and amino acids were seen in spectra for all patients, irrespective of the time of spectroscopy after the onset of combined medical and surgical therapy. Acetate and pyruvate disappeared after 1 week of combined treatment.

CONCLUSION

It was concluded that spectral patterns for brain abscesses are consistent and specific and can assist in the noninvasive diagnosis of abscesses. Responses to combined treatment could be monitored by showing the changes in metabolite patterns in serial spectroscopic studies.

Brain abscess and brain tumor: discrimination with in vivo H-1 MR spectroscopy

PURPOSE

To determine the ability to differentiate brain abscess from cystic or necrotic brain tumor with hydrogen-1 magnetic resonance (MR) spectroscopy.

MATERIALS AND METHODS

H-1 MR spectroscopy was prospectively performed in seven consecutive patients with pyogenic brain abscess and in seven consecutive patients with necrotic or cystic brain tumor (five patients with glioblastoma and one each with pilocytic astrocytoma and metastasis from lung cancer) in whom radiologic images depicted ring-shaped areas of contrast material enhancement (indicative of a cystic or necrotic mass). Assignment of resonance peaks to metabolites was based on reports in the literature.

RESULTS

In six of seven patients with abscess, there were various resonances attributed to lactate, valine, alanine, leucine, acetate, succinate, and unidentified metabolites (2.2, 2.9, 3.2, 3.4, and 3.8 ppm). In six of seven patients with tumor, there was only a resonance attributed to lactate. One patient with a tumor had an unidentified peak at 0.9 ppm (presumably attributed to lipid) in addition to the peak attributed to lactate.

CONCLUSION

Spectral patterns from in vivo H-1 MR spectroscopy may permit differentiation of brain abscess from necrotic or cystic tumor.

Diagnosis of brain abscess by magnetic resonance spectroscopy. Report of two cases

Two cases of brain abscess were diagnosed by combining magnetic resonance spectroscopy (MRS) and magnetic resonance (MR) imaging. The resonances observed in vivo were assigned by means of an in vitro MRS study of the exudates extracted during surgical aspiration of the abscesses. The technique of MRS was demonstrated to be very powerful in the differential diagnosis of brain abscesses from other brain pathologies such as neoplasms. Amino acids, probably originating from extracellular proteolysis, and other compounds, such as acetate, arising from bacterial metabolism, were visible in the MRS spectra of the abscess, whereas they are not present in spectra of neoplasms. In this sense, MRS complemented the information provided by MR imaging to achieve a correct diagnosis of brain abscesses and could be added to routine MR examinations with only a small increase in cost and time.

Expression of various TGF-beta isoforms and type I receptor in necrotizing human brain lesions

It is known that transforming growth factor beta (TGF-beta) is involved in the modulation of cell growth, differentiation, and repair following injury. We performed an immunohistochemical study of human brain autopsy and biopsy material for the expression of TGF-beta isoforms beta 1, beta 2 and beta 3, and TGF-beta receptor (T beta R) type I in different cells of necrotizing lesions such as infarction and abscess, and compared them with controls. Various cell types, both inside and in the proximity of lesions, showed immunoreactivity indicating the presence of all three isoforms. Significant values of immunoreaction for various TGF-beta s and T beta R-I were observed in cells such as astrocytes, macrophages, neurons, microvascular endothelial cells, and granulocytes. In the control cases, comprising biopsy material without necrotizing lesions, a prominent TGF-beta 2 immunoreactivity was observed in glial cells and neurons. TGF-beta 1 and TGF-beta 3 reactivity in controls, when compared with TGF-beta 2, was less. T beta R-I antiserum showed clear and distinct signals in the same type of cells as for TGF-beta s in the necrotizing lesions with varying values of significance. Our findings suggest that TGF-beta s and their receptor type I are involved in reactive processes around necrotizing human brain lesions like glial and macrophage responses, angiogenesis, and deposition of extracellular matrix.

Posttraumatic gas-containing brain abscess caused by Clostridium perfringens with unique simultaneous fungal suppuration by Myceliophthora thermophila: case report

OBJECTIVE AND IMPORTANCE

Gas-containing brain abscesses are rare, and the vast majority are caused by Clostridium perfringens. Significant simultaneous fungal infection in a bacterial abscess is even rarer. We present such a case and review the literature.

CLINICAL PRESENTATION

A 21-month-old male patient sustained a penetrating head injury in a barnyard, developed a gas-containing left parietal brain abscess, and presented with high fever, galeal swelling, and seizure.

INTERVENTION

The patient initially underwent debridement of his wound and then repeated aspirations. The initial cultures revealed pure growth of Clostridium perfringens. Despite appropriate antibiotic therapy, serial neuroimaging did not demonstrate a decrease in the size of the cavity. An excision had to be undertaken 6 weeks after the injury. The culture from the excised specimen revealed an unexpected growth of a saprophytic and opportunistic fungus, Myceliophthora thermophila. Antifungal treatment consisting of the administration of liposomal amphotericin B and itraconazole was then performed. The child was well and neurologically intact 6 months after the excision.

CONCLUSION

Our review revealed 38 cases of clostridial brain abscess in the literature. Despite the reputation of the organism, the outcome with clostridial brain abscesses was relatively benign. The main characteristics of clostridial brain abscesses are highlighted, with reference to their optimal treatment. Our review also revealed that fungal infection after a penetrating head injury is extremely rare and often fatal. Our case seems to be the first in the medical literature with growth of M. thermophila as a causative agent for intracranial suppuration.

1H MRS of human brain abscesses in vivo and in vitro

Five patients, each with a brain abscess, were examined by means of 1H MR spectroscopic imaging in vivo. The aspirated pus was analyzed in vitro by means of 1D and 2D COSY 1H MRS. In addition to resonance lines from compounds (lactate, alanine and lipids) often found in the spectra from intracranial tumors, resonance lines were detected from a number of markers of infectious involvement (acetate, succinate, and various amino acids). These results suggest that 1H MRS in vivo might contribute in establishing noninvasively a differential diagnosis between brain abscess and tumor.

Expression of basic fibroblast growth factor, nerve growth factor, platelet-derived growth factor and transforming growth factor-beta in human brain abscess

We correlated the histopathological findings of six human brain abscesses with the expression of basic fibroblast growth factor (bFGF), nerve growth factor (NGF), platelet-derived growth factor (PDGF) and transforming growth factor-beta (TGF beta). The clinical courses ranged from 1 month to 1 year and viridans streptococcus was the major pathogen. In early abscesses, we demonstrated strong bFGF and moderate NGF and PDGF immunoreactivities in neutrophils and monocytes/macrophages infiltrating the abscess wall and in the fibrin layer lining the abscess center. In the subacute cases, growth of capillaries and fibroblasts into the fibrin layer and deposition of collagen resulted in the formation of a mesodermal layer between the abscess center and the outer gliotic layer. The proliferative non-neural cells (endothelial cells, fibroblasts and glial cells) expressed mild to strong bFGF, NGF and PDGF immunoreactivities, while strong TGF beta staining was seen in the extracellular matrix. A loss of growth factor expression and increased fibrosis was seen in the chronic case. These findings suggest that bFGF, NGF, PDGF and TGF beta produced by the continued influx of leukocytes and by the proliferating non-neural cells may mediate various steps of defense mechanisms and wound healing such as angiogenesis, fibrogenesis and gliosis.

Discordance between F-18 fluorodeoxyglucose uptake and contrast enhancement in a brain abscess

A 29-year-old human immunodeficiency virus-negative intravenous drug abuser with a right hemispheric staphylococcal brain abscess underwent PET imaging of 18F-fluorodeoxyglucose (FDG) brain uptake. Diffuse right cortical hypometabolism was noted, as well as crossed cerebellar diaschisis. Unlike previous PET findings on FDG uptake in a brain abscess, however, the most intense uptake of FDG was found within the abscess and not in the contrast-enhancing walls.

Penetration of intravenous antibiotics into brain abscesses

INTRA-ABSCESS CONCENTRATIONS OF the intravenously administered latamoxef (LMOX, moxalactam in the United States) and cefotetan (CTT), were studied in 11 patients with intracranial abscess. None of these patients underwent surgical ablation of the abscess. In all cases, the abscess was aspirated, and multiple aspirations were required in five patients. Antibiotic concentrations in 18 aspirates were, therefore, determined by the agar well method. LMOX concentrations in 16 aspirates drawn from nine brain abscess cases ranged from 0 to 10.9 micrograms/ml, with a mean (standard deviation) of 4.18 (3.04) micrograms/ml. The CTT concentration in one patient with a brain abscess was 8.51 micrograms/ml, and the LMOX concentration in the one remaining patient with subdural empyema was 5.20 micrograms/ml. In one patient, the serum-to-pus penetration rate of LMOX was estimated to be 0.11 against the peak value of the concentration in serum or 0.44 against the simultaneously obtained level in serum. Significantly higher concentrations of LMOX were produced in abscess cavities with multiple-dose administration or by prior drainage of pus. More-advanced stages of local inflammation, as demonstrated by computed tomography, correlated with higher concentrations. However, the routine indexes of systemic inflammation, such as body temperature, white blood cell count, and level of C-reactive protein in serum, cannot be used to predict the concentration present in intracerebral pus. A tendency for LMOX concentrations in pus obtained after single dose-administration to decrease with increasing duration from symptom onset to sampling was observed but was not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of microglia and macrophages in the central nervous system of rats: definition of the differential expression of molecules using standard and novel monoclonal antibodies in normal CNS and in four models of parenchymal reaction

This report describes the development of a new panel of monoclonal antibodies produced following immunization of mice with cultured rat microglial cells. Using these new reagents and previously defined antibodies that bind to microglia or macrophages, the responses of parenchymal microglia, perivascular "microglial" cells, and infiltrating macrophage/monocytes were examined in 4 divergent models of central nervous system reaction. These were brain abscess, experimental allergic encephalomyelitis, Wallerian degeneration, and stab wound. No single new antibody was specific only for microglia; all antibodies positively staining microglial cells also labeled various subsets of macrophage/monocytic cells in normal tissues of the immune system. Moreover, the results indicate that microglia are capable of different levels and a variety of types of response, as defined by the molecules they elaborate. These findings suggest that these CNS resident cells belong to the extended monocyte/macrophage/dendritic cell family and that they do not respond in a stereotypic manner to all forms of CNS insult.

Alzheimer's amyloid precursor protein accumulates within axonal swellings in human brain lesions

By using a monoclonal antibody and polyclonal antibodies to human beta amyloid precursor protein (APP), we immunohistochemically examined axonal swellings (spheroids). The immunoreactivity of APP was observed in numerous spheroids, which were found around the areas of old cerebral infarctions, in the globus pallidus with Hallervorden-Spatz disease as well as in or around brain abscesses. The axonal swellings were not immunolabeled with beta protein. These results implied that APP accumulated in spheroids regardless of beta protein depositions.