Electron microscopic studies of esophageal wall structures in patients with achalasia: casting more light on unresolved aspects of pathogenesis.

BACKGROUND/AIMS: Previous investigations of esophageal tissue and serum probes failed to identify a common etiologic agent predisposing to, triggering or causing achalasia. In order to further examine the detailed pathologic processes resulting in achalasia we performed electron-microscopic studies of muscle biopsies taken from the LES high pressure zone in patients undergoing surgery--either Heller myotomy or esophageal resection. METHODOLOGY: Smooth muscle biopsies with a 20 x 15-mm longitudinal segment of the myenteric plexus from the distal esophagus (lower border of the esophageal incision) in patients undergoing Heller myotomy for achalasia were taken. In patients with end-stage achalasia and mega-esophagus with esophageal resection, the complete esophageal body was available. For electron microscopy, ultrathin sections were contrasted with uranyl-acetate and plumbic citrate. The photographs were taken by a digitalized electron-microscope (ZEISS, Leo 905). RESULTS: A striking finding was the large number of mast cells in the region of the smooth muscle layers as well as in the surrounding connective tissue and also in close vicinity to the nerve cells and to the nerve fibres. The smooth muscle cells in these regions were very often stained less intensively, and they showed signs of an acute degenerative process. CONCLUSION: Our electron microscopic studies suggest that mast cells may play an important role in the secondary pathogenesis of achalasia. Esophageal retention and bacterial overgrowth with stasis esophagitis causing mucosal injury may be a mechanism of increased antigen exposure.

Reduction of interstitial cells of Cajal (ICC) associated with neuronal nitric oxide synthase (n-NOS) in patients with achalasia.

BACKGROUND: The etiology of achalasia is still unknown. The current theories of chronic inflammation leading to autoimmune response with destruction and loss of the inhibitory myenteric ganglion cells enlighten its pathogenesis in a limited way only. Interstitial cells of Cajal (ICC) have been shown to be involved in nitrergic neurotransmission of the lower esophageal sphincter (LES). AIM: To investigate the significance of ICC and neuronal nitric oxide synthase (n-NOS) in esophageal wall tissue of patients undergoing surgery for achalasia. METHODS: In 53 patients with a median age of 45 (6-78) yr undergoing surgery for achalasia, the immunoreactivity of ICC (CD117/c-kit) and n-NOS was assessed. In 42 patients, biopsies were taken from the LES high-pressure zone during Heller myotomy, whereas in 11 patients with end-stage achalasia and a decompensated megaesophagus, the complete esophagus was resected. A semiquantitative analysis was carried out and ICC and n-NOS impairments were classified into four grades. Staining intensity was correlated with preoperative clinical, radiologic, and manometric findings and with long-term postoperative Eckardt score. RESULTS: Grade III/IV ICC reduction (severe reduction to complete loss) was seen in 59.5% of all biopsy specimens of the LES high-pressure zone. Patients with grade III/IV ICC reduction had a significantly longer duration of achalasia symptoms (3 [0-43] yr) than patients with minor to marked (grade I/II) impairment (1 [0-16] yr, P= 0.028). A majority (72.5%) of tissue samples revealed severe reduction to complete loss of n-NOS immunoreactivity. The preoperative Eckardt score was statistically significantly different between patients with grade I/II and those with grade III/IV n-NOS reductions (P= 0.031). CD117 (c-kit) positivity was statistically significantly correlated with n-NOS staining intensity (correlation coefficient r= 0.781, P < 0.0001). CONCLUSION: The present results suggest that in the pathogenesis of achalasia, especially in the development of the LES high-pressure zone, depletion of ICC networks and potential changes in the electrical activity of smooth muscle cells may play a crucial role. The reduction in CD117-positive ICC in a few patients also seemed to be of relevance, even if the cells of Auerbach's plexus were unscathed. The associated reduced NOS release might underlie the profound ICC impairment and could possibly be responsible for the lack of LES relaxation, because of missing inhibitory neurotransmission. It is unclear, however, whether the ICC loss is primarily caused by the accelerated attrition of mature cells or their impaired regeneration.

Differentiation of fibroblastic meningiomas from other benign subtypes using diffusion tensor imaging.

PURPOSE: To differentiate fibroblastic meningiomas, usually considered to be of a hard consistency, from other benign subtypes using diffusion tensor imaging (DTI). MATERIALS AND METHODS: From DTI data sets of 30 patients with benign meningiomas, we calculated diffusion tensors and mean diffusivity (MD) and fractional anisotropy (FA) maps as well as barycentric maps representing the geometrical shape of the tensors. The findings were compared to postoperative histology. The study was approved by the local ethics committee, and informed consent was given by the patients. RESULTS: According to one-way analysis of variance (ANOVA), FA was the best parameter to differentiate between the subtypes (F=32.2; p<0.0001). Regarding tensor shape, endothelial meningiomas were represented by spherical tensors (80%) corresponding to isotropic diffusion, whereas the fibroblastic meningiomas showed a high percentage (43%) of nonspherical tensors, indicating planar or longitudinal diffusion. The difference was highly significant (F=28.4; p<0.0001) and may be due to the fascicular arrangement of long spindle-shaped tumor cells and the high content of intra- and interfascicular fibers as shown in the histology. In addition, a capsule-like rim of the in-plane diffusion surrounded most meningiomas irrespective of their histological type. CONCLUSION: If these results correlate to the intraoperative findings of meningioma consistency, DTI-based measurement of FA and analysis of the shape of the diffusion tensor is a promising method to differentiate between fibroblastic and other subtypes of benign meningiomas in order to get information about their "hard" or "soft" consistency prior to removal.

Spectrum of histopathologic findings in patients with achalasia reflects different etiologies.

BACKGROUND: The etiology of achalasia is still unknown. The aim of the present study was to elucidate its underlying pathologies and their chronology by investigation of esophageal specimens in patients undergoing surgery (esophageal resection or myotomy) for achalasia. METHODS: In 17 patients with achalasia, histopathologic examinations of the esophageal wall focussing on the myenteric plexus were performed. Preoperative diagnosis was based on clinical evaluation, esophagogastroscopy, barium esophagogram in all, and esophageal manometry in eight patients. The median age at the time of surgery was 54 years (range: 14-78 years). In eight cases, the complete esophageal, body and in nine cases a smooth muscle biopsy including parts of the myenteric plexus from the distal part of the esophagus (high pressure zone) was available. The tissue specimens were fixed in formalin and embedded in paraffin. The staining procedures were hematoxylin and eosin (HE), Elastica van Gieson (EvG), and periodic acid-Schiff (PAS) reaction. Immunohistochemical examinations were performed with antibodies against B and T lymphocytes, neurofilament, protein gene-related product (PGP 9.5), S-100 protein, myosin, desmin, smooth muscle actin and substance P. RESULTS: In 13 of 17 patients, a significant reduction of the number of intramural ganglion cells was present. Common findings were a severe fibrosis of the smooth muscle layer (10/17) and obvious myopathic changes of the smooth muscle cells (5/17). Staining for B and T lymphocytes found signs of inflammation in mucosal and muscular areas. Three patients exhibited a marked invasion of eosinophilic granulocytes of the muscularis propria (eosinophilia). Esophageal carcinoma had developed in three patients (squamous cell carcinoma in two and carcinoma in situ in another patient with Barrett's esophagus and high-grade dysplasia). Severe inflammatory reactions (neural, eosinophilic and mucosal) dominated in patients with a longstanding history of achalasia (>10 years) as well as a marked endomysial fibrosis. CONCLUSIONS: The histopathological investigations of the esophageal wall in 17 patients undergoing esophageal resection or myotomy for achalasia suggest that the reduction of intramural ganglion cells might be a secondary change, probably due to inflammation triggered by autoimmune mechanisms or a chronic degenerative process of the central and/or peripheral part of the vagal nerve. The primary lesion could also be a severe myopathy of the smooth muscle cells.

Brain edema and intracerebral necrosis caused by transcranial low-frequency 20-kHz ultrasound: a safety study in rats.

BACKGROUND AND PURPOSE: Ultrasound-accelerated thrombolysis is a promising approach toward acute stroke treatment. In previous in vitro studies, we demonstrated enhanced thrombus destruction induced by 20-kHz ultrasound. However, little is known about biological interactions of low-frequency ultrasound with brain tissue. The aim of this in vivo MRI study was to assess safety aspects of transcranial low-frequency ultrasound in rats. METHODS: The cranium of 33 male Wistar rats was sonificated for 20 minutes (20-kHz continuous wave). Power output was varied between 0 and 2.6 W/cm2. Tympanal and rectal temperature was monitored. Diffusion-weighted imaging and T2-weighted imaging was performed before and 4 hours, 24 hours, and 5 days after sonification. Apparent diffusion coefficients (ADCs) and T2 relaxation time (T2-RT) were measured in regions of interest in the cortex and the basal ganglia. The animals were euthanized for histological evaluation thereafter. RESULTS: Tympanal temperature increased significantly during insonation with 1.1 and 2.6 W/cm2. ADCs decreased significantly at 0.5 and 1.1 W/cm2, indicating cytotoxic edema. T2-RT increased significantly in the 0.5 and 1.1 W/cm2 group, consistent with vasogenic edema. No changes were detectable in the low-power output group (0.2 W/cm2). After sonification with 2.6 W/cm2, a significant loss of neurons could be detected on histopathology. Furthermore, 3 animals developed circumscript cortical lesions that could be identified as parenchymal necrosis. CONCLUSIONS: Low-frequency ultrasound caused vasogenic and cytotoxic brain edema and intracerebral necrosis in a dose-dependent fashion. This study indicates therapeutic low-frequency ultrasound as being potentially harmful and underlines the necessity of careful evaluation in further animal models.

A disintegrin-metalloproteinase prevents amyloid plaque formation and hippocampal defects in an Alzheimer disease mouse model.

Alzheimer disease (AD) is characterized by excessive deposition of amyloid beta-peptides (A beta peptides) in the brain. In the nonamyloidogenic pathway, the amyloid precursor protein (APP) is cleaved by the alpha-secretase within the A beta peptide sequence. Proteinases of the ADAM family (adisintegrin and metalloproteinase) are the main candidates as physiologically relevant alpha-secretases, but early lethality of knockout animals prevented a detailed analysis in neuronal cells. To overcome this restriction, we have generated transgenic mice that overexpress either ADAM10 or a catalytically inactive ADAM10 mutant. In this report we show that a moderate neuronal overexpression of ADAM10 in mice transgenic for human APP([V717I]) increased the secretion of the neurotrophic soluble alpha-secretase-released N-terminal APP domain (APPs alpha), reduced the formation of A beta peptides, and prevented their deposition in plaques. Functionally, impaired long-term potentiation and cognitive deficits were alleviated. Expression of mutant catalytically inactive ADAM10 led to an enhancement of the number and size of amyloid plaques in the brains of double-transgenic mice. The results provide the first in vivo evidence for a proteinase of the ADAM family as an alpha-secretase of APP, reveal activation of ADAM10 as a promising therapeutic target, and support the hypothesis that a decrease in alpha-secretase activity contributes to the development of AD.