Immunosuppressive role of BDNF in therapy-induced neuroendocrine prostate cancer

Prostate stromal cells play a crucial role in the promotion of tumor growth and immune evasion in the tumor microenvironment (TME) through intricate molecular alterations in their interaction with prostate cancer (PCa) cells. While the impact of these cells on establishing an immunosuppressive response and influencing PCa aggressiveness remains incompletely understood. Our study shows that the activation of the leukemia inhibitory factor (LIF)/LIF receptor (LIFR) pathway in both prostate tumor and stromal cells, following androgen deprivation therapy (ADT), leads to the development of an immunosuppressive TME. Activation of LIF/LIFR signaling in PCa cells induces neuroendocrine differentiation (NED) and upregulates immune checkpoint expression. Inhibition of LIF/LIFR attenuates these effects, underscoring the crucial role of LIF/LIFR in linking NED to immunosuppression. Prostate stromal cells expressing LIFR contribute to NED and immunosuppressive marker abundance in PCa cells, while LIFR knockdown in prostate stromal cells reverses these effects. ADT-driven LIF/LIFR signaling induces brain-derived neurotrophic factor (BDNF) expression, which, in turn, promotes NED, aggressiveness, and immune evasion in PCa cells. Clinical analyses demonstrate elevated BDNF levels in metastatic castration-resistant PCa (CRPC) and a positive correlation with programmed death-ligand 1 (PDL1) and immunosuppressive signatures. This study shows that the crosstalk between PCa cells and prostate stromal cells enhances LIF/LIFR signaling, contributing to an immunosuppressive TME and NED in PCa cells through the upregulation of BDNF.

CHRM4/AKT/MYCN upregulates interferon alpha-17 in the tumor microenvironment to promote neuroendocrine differentiation of prostate cancer

Current treatment options for prostate cancer focus on targeting androgen receptor (AR) signaling. Inhibiting effects of AR may activate neuroendocrine differentiation and lineage plasticity pathways, thereby promoting the development of neuroendocrine prostate cancer (NEPC). Understanding the regulatory mechanisms of AR has important clinical implications for this most aggressive type of prostate cancer. Here, we demonstrated the tumor-suppressive role of the AR and found that activated AR could directly bind to the regulatory sequence of muscarinic acetylcholine receptor 4 (CHRM4) and downregulate its expression. CHRM4 was highly expressed in prostate cancer cells after androgen-deprivation therapy (ADT). CHRM4 overexpression may drive neuroendocrine differentiation of prostate cancer cells and is associated with immunosuppressive cytokine responses in the tumor microenvironment (TME) of prostate cancer. Mechanistically, CHRM4-driven AKT/MYCN signaling upregulated the interferon alpha 17 (IFNA17) cytokine in the prostate cancer TME after ADT. IFNA17 mediates a feedback mechanism in the TME by activating the CHRM4/AKT/MYCN signaling-driven immune checkpoint pathway and neuroendocrine differentiation of prostate cancer cells. We explored the therapeutic efficacy of targeting CHRM4 as a potential treatment for NEPC and evaluated IFNA17 secretion in the TME as a possible predictive prognostic biomarker for NEPC.

Targeting PKLR/MYCN/ROMO1 signaling suppresses neuroendocrine differentiation of castration-resistant prostate cancer

Conventional treatment of prostate cancer (PCa) uses androgen-deprivation therapy (ADT) to inhibit androgen receptor (AR) signaling-driven tumor progression. ADT-induced PCa recurrence may progress to an AR-negative phenotype with neuroendocrine (NE) histologic features, which are associated with metabolic disturbances and poor prognoses. However, the metabolic pathways that regulate NE differentiation (NED) in PCa remain unclear. Herein, we show a regulatory mechanism in NED-associated metabolism dysfunction induced by ADT, whereby overexpression of pyruvate kinase L/R (PKLR) mediates oxidative stress through upregulation of reactive oxygen species modulator 1 (ROMO1), thereby promoting NED and aggressiveness. ADT mediates the nuclear translocation of PKLR, which binds to the MYCN/MAX complex to upregulate ROMO1 and NE-related genes, leading to altered mitochondrial function and NED of PCa. Targeting nuclear PKLR/MYCN using bromodomain and extra-terminal motif (BET) inhibitors has the potential to reduce PKLR/MYCN-driven NED. Abundant ROMO1 in serum samples may provide prognostic information in patients with ADT. Our results suggest that ADT resistance leads to upregulation of PKLR/MYCN/ROMO1 signaling, which may drive metabolic reprogramming and NED in PCa. We further show that increased abundance of serum ROMO1 may be associated with the development of NE-like PCa.

TCF7L1 regulates cytokine response and neuroendocrine differentiation of prostate cancer

Neuroendocrine differentiation (NED) is associated with WNT signaling activation and can be significantly observed after failure of androgen-deprivation therapy (ADT) for prostatic adenocarcinomas. Cytokine signaling is stimulated in NED prostate cancer; however, how ADT-upregulated WNT signaling promotes activation of cytokine signaling and contributes to NED of prostate cancer is poorly understood. In this study, we identified ADT-mediated upregulation of transcription factor 7 like 1 (TCF7L1), which increases the cytokine response and enhances NED of prostate cancer through interleukin (IL)-8/C-X-C motif chemokine receptor type 2 (CXCR2) signaling activation. ADT induced the secretion of WNT4 which upon engagement of TCF7L1 in prostate cancer cells, enhanced IL-8 and CXCR2 expressions. TCF7L1 directly binds to the regulatory sequence region of IL-8 and CXCR2 through WNT4 activation, thus upregulating IL-8/CXCR2 signaling-driven NED and cell motility. Analysis of prostate tissue samples collected from small-cell neuroendocrine prostate cancer (SCPC) and castration-resistant prostate cancer (CRPC) tumors showed an increased intensity of nuclear TCF7L1 associated with CXCR2. Our results suggest that induction of WNT4/TCF7L1 results in increased NED and malignancy in prostate cancer that is linked to dysregulation of androgen receptor signaling and activation of the IL-8/CXCR2 pathway.

Abstract 725: LIFR promotes SUCLG2-dependent castration resistance and neuroendocrine differentiation of prostate cancer

Neuroendocrine (NE) differentiation is a well-recognized phenotypic change of prostate cancer after androgen-deprivation therapy (ADT) that ultimately develops an aggressive subtype. An increasing number of patients with NE histologic type prostate cancer present with metabolic genes disorder. However, the metabolic pathways that influence the malignant transformation and the NE differentiation of prostate cancer remain unclear. In this study, we found that ADT induced the upregulation of leukemia inhibitory factor receptor (LIFR), which contributes to the expression of succinate-CoA ligase GDP-forming beta subunit (SUCLG2), thus activating metabolic reprogramming to enable NE differentiation and increase aggressiveness. Activated LIF-LIFR-STAT3 axis stimulates SUCLG2 expression, subsequently upregulating glucose metabolism and the NE differentiation of prostate cancer. SUCLG2 knockdown markedly reduced mitochondrial DNA content and inhibited the enzymatic activity of succinyl-CoA synthetase and nucleoside diphosphate kinase (NDPK) in prostate cancer cells. SUCLG2 overexpression promoted androgen-independent proliferation; however, SUCLG2 knockdown suppressed NE differentiation and the ADT resistance of prostate cancer cells. Analysis of prostate tissue samples showed an increased intensity of LIFR associated with SUCLG2 in castration-resistant prostate cancer tumors. Our study identifies SUCLG2 as a potential prognostic marker of ADT-resistant prostate cancer and suggests it could be a target for prostate cancer treatment.

Citation Format: Hsiu-Lien Yeh, Shian-Ren Lin, Kuo-Ching Jiang, Wei-Hao Chen, Yen-Nien Liu. LIFR promotes SUCLG2-dependent castration resistance and neuroendocrine differentiation of prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 725.

EGFR-upregulated LIFR promotes SUCLG2-dependent castration resistance and neuroendocrine differentiation of prostate cancer

Neuroendocrine (NE) differentiation is a well-recognized phenotypic change of prostate cancer after androgen deprivation therapy (ADT), and it ultimately develops into an aggressive subset of this disease. However, the contribution of signaling pathways that lead to metabolic disorders and NE differentiation of prostate cancer remains unclear. In this study, we identified that ADT induced upregulation of the succinate-CoA ligase GDP-forming beta subunit (SUCLG2), which regulates succinate metabolism and NE differentiation of prostate cancer. We demonstrated a connection that upregulation of epidermal growth factor receptor (EGFR)-leukemia inhibitory factor receptor (LIFR) signaling induced SUCLG2 expression in prostate cancer cells. The LIFR is upregulated by nuclear EGFR, which acts as a transcriptional regulator, directly binds to the LIFR promoter, and drives NE differentiation and glycolysis of prostate cancer. LIFR upregulation is associated with SUCLG2, which increased succinate synthesis and enzymatic activities of mitochondrial nucleoside diphosphate kinase (NDPK) in prostate cancer cells. Knockdown of SUCLG2 suppressed NE differentiation in cultured cells and reduced prostate tumor growth in a xenograft model. Analysis of prostate tissue samples showed increased intensity of nuclear EGFR associated with the LIFR and SUCLG2 in castration-resistant prostate cancer tumors. Our study provides a mechanism whereby ADT upregulates EGFR-LIFR signaling that activates SUCLG2, which subsequently stimulates the metabolic changes associated with NE differentiation and aggressive prostate cancer phenotype.

Abstract 304: Androgen deprivation induces epithelial to mesenchymal transition and neuroendocrine differentiation of prostate cancer via LIF-mediated phosphorylation of Smad2

The current therapies for prostate cancer, which can either be androgen-sensitive or androgen-insensitive ones, are based on AR-targeting approaches; however, there is no available treatment for neuroendocrine prostate cancer (NEPC). We previously identified the leukemia inhibitory factor (LIF), which is stimulated by androgen deprivation therapy (ADT). Here, we further elucidated the physiological relevance of LIF, whereby the high LIF output is associated with the activation of epithelial-to-mesenchymal transition (EMT), and neuroendocrine differentiation of prostate cancer cells through stimulation of transforming growth factor (TGF)-β signaling. We have elucidated the effect of LIF on inducing the EMT and NEPC progression through the stimulated TGF-β signaling via phosphorylation of Smad2. We also demonstrated that the inverse relationship between inhibition of AR signaling and induction of LIF-Smad2 signaling may predispose prostate cancer to metastasis. Importantly, an established activation in prostate cancer cells was shown between recombinant LIF protein and phosphorylation of Smad2, supporting the connection between LIF and p-Smad2. This was supported by the results obtained in high-LIF samples with elevated expression of p-Smad2 in tissues from high-grade prostate cancer. This study highlights the role of the important crosstalk between the LIF and TGF-β signaling pathways may exist and provide a new direction for investigating NEPC development.

Citation Format: Yen-Nien Liu, Shian-Ren Lin, Ntlotlang Mokgautsi, Hsiu-Lien Yeh, Jiaoti Huang. Androgen deprivation induces epithelial to mesenchymal transition and neuroendocrine differentiation of prostate cancer via LIF-mediated phosphorylation of Smad2 [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 304.

Androgen deprivation-induced ZBTB46-PTGS1 signaling promotes neuroendocrine differentiation of prostate cancer

Androgen receptor (AR) targeting is an important therapeutic strategy for treating prostate cancer. Most tumors progress to castration-resistant prostate cancer (CRPC) and develop the neuroendocrine (NE) phenotype under androgen deprivation therapy (ADT). The molecular basis for NE transdifferentiation after ADT remains incompletely understood. Herein, we show that an immunocyte expression protein, ZBTB46, induces inflammatory response gene expression and contributes to NE differentiation of prostate cancer cells. We demonstrated a molecular mechanism whereby ZBTB46 can be regulated by the androgen-responsive gene, SPDEF, and is associated with NE prostate cancer (NEPC) differentiation. In addition, ZBTB46 acts as a transcriptional coactivator that binds to the promoter of prostaglandin-endoperoxide synthase 1 (PTGS1) and transcriptionally regulated PTGS1 levels. Overexpression of ZBTB46 decreases the sensitivity of the combination of enzalutamide and a PTGS1 inhibitor; however, knockdown of ZBTB46 sensitizes the PTGS1 inhibitor and reduces tumor malignancy. ZBTB46 is inversely correlated with SPDEF and is increased in higher tumor grades and small-cell NE prostate cancer (SCNC) patients, which are positively associated with PTGS1. Our findings suggest that the induction of ZBTB46 results in increased PTGS1 expression, which is associated with NEPC progression and linked to the dysregulation of the AR-SPDEF pathway.

Abstract A031: Androgen deprivation therapy-induced TGFBI signaling promotes EMT and bone metastasis of prostate cancer

Metastatic progression in patients with prostate cancer is common despite pharmacologic inhibition of androgen receptor signaling. This drug resistance is associated with increased signaling through the transforming growth factor-β (TGF-β) signaling pathway. We found the type I/II/IV collagen-binding protein transforming growth factor-β (TGF-β)-induced (TGFBI) is an important factor in the epithelial-to-mesenchymal transition (EMT) and malignant progression of prostate cancer. We identified that an androgen-responsive gene, SPDEF, navigates between AR and TGFβ signaling during prostate cancer progression to metastasis though a physical interaction with the promoter region of the TGFBI gene. We show that loss of AR-regulated SPDEF induces TGFBI expression in prostate cancer cells, leading to drastic and aggressive physiologic changes. Furthermore, we confirmed the negative correlation between SPDEF and TGFβ singling in prostate cancer patients and demonstrated that ADT can reduce SPDEF and increase TGFβ signaling. Our results support an inhibitory role of the AR on TGFβ signaling through SPDEF-mediated suppression of TGFBI, and that disruption of this pathway promotes metastatic progression in prostate cancer.

Citation Format: Yen-Nien Liu, Wei-Yu Chen, Yuan-Chin Tsai, Hsiu-Lien Yeh, Florent Suau, Jiaoti Huang. Androgen deprivation therapy-induced TGFBI signaling promotes EMT and bone metastasis of prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr A031.

Disruption of ETV6 leads to TWIST1-dependent progression and resistance to epidermal growth factor receptor tyrosine kinase inhibitors in prostate cancer

BACKGROUND

ETS variant gene 6 (ETV6) is a putative tumor suppressor and repressed by epidermal growth factor receptor (EGFR) signaling in prostate cancer. Since EGFR antagonists seem ineffective in castration-resistant prostate cancer (CRPC), we aim to study the role of ETV6 in the development of drug resistance.

METHODS

Etv6 target gene was validated by ChIP and promoter reporter assays. Correlation of ETV6 and TWIST1 was analyzed in human clinical datasets and tissue samples. Migration, invasion, and metastasis assays were used to measure the cellular responses after perturbation of ETV6 -TWIST1 axis. Proliferation and tumor growth in xenograft model were performed to evaluate the drug sensitivities of EGFR-tyrosine kinase inhibitors (TKIs).

RESULTS

ETV6 inhibits TWIST1 expression and disruption of ETV6 promotes TWIST1-dependent malignant phenotypes. Importantly, ETV6 is required to the anti-proliferation effects of EGFR-TKIs, partly due to the inhibitory function of ETV6 on TWIST1. We also found that EGFR-RAS signaling is tightly controlled by ETV6, supporting its role in TKI sensitivity.

CONCLUSIONS

Our study demonstrates that disruption of ETV6 contributes to EGFR-TKI resistance, which is likely due to derepression of TWIST1 and activation of EGFR-RAS signaling. Our results implicate ETV6 as a potential marker for predicting efficacy of an EGFR-targeted anticancer approach. Combination treatment of TWIST1 inhibitors could sensitize the anti-proliferation effects of EGFR-TKIs.

Loss of SPDEF and gain of TGFBI activity after androgen deprivation therapy promote EMT and bone metastasis of prostate cancer

Androgen deprivation therapy (ADT) targeting the androgen receptor (AR) is a standard therapeutic regimen for treating prostate cancer. However, most tumors progress to metastatic castration-resistant prostate cancer after ADT. We identified the type 1, 2, and 4 collagen-binding protein transforming growth factor-β (TGFβ)-induced protein (TGFBI) as an important factor in the epithelial-to-mesenchymal transition (EMT) and malignant progression of prostate cancer. In prostate cancer cell lines, AR signaling stimulated the activity of the transcription factor SPDEF, which repressed the expression of TGFBI ADT, AR antagonism, or overexpression of TGFBI inhibited the activity of SPDEF and enhanced the proliferation rates of prostate cancer cells. Knockdown of TGFBI suppressed migration and proliferation in cultured cells and reduced prostate tumor growth and brain and bone metastasis in xenograft models, extending the survival of tumor-bearing mice. Analysis of prostate tissue samples collected before and after ADT from the same patients showed that ADT reduced the nuclear abundance of SPDEF and increased the production of TGFBI. Our findings suggest that induction of TGFBI promotes prostate cancer growth and metastasis and can be caused by dysregulation or therapeutic inhibition of AR signaling.

Abstract 4467: ETV6 is a tumor suppressor regulated by EGFR-miR-96 pathway in prostate cancer

ETV6 is an ETS transcription factor and a putative tumor suppressor in prostate cancer according to several genomic analyses. However, its cellular functions and upstream regulating signaling remain unclear. We demonstrated that ETV6 suppresses the prostate cancer progression and that ETV6 levels are negatively associated with advanced prostate cancer, supporting the idea that ETV6 acts as a tumor suppressor. Furthermore, ETV6 can be regulated by epidermal growth factor receptor (EGFR) signaling through microRNA (miR)-mediated downregulation. One of the miRs, miR-96, can be transcriptionally-regulated by nuclear EGFR. The association patterns connecting miR-96, EGFR activation, and ETV6 were further validated in the clinical tissue samples. We proposed an EGFR-miR-96-ETV6 signaling pathway in promoting prostate cancer.

Note: This abstract was not presented at the meeting.

Citation Format: Yen-Nien Liu, Yuan-Chin Tsai, Wei-Yu Chen, Man Kit Siu, Hsiu-Lien Yeh. ETV6 is a tumor suppressor regulated by EGFR-miR-96 pathway in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4467. doi:10.1158/1538-7445.AM2017-4467

MicroRNA-34a regulates WNT/TCF7 signaling and inhibits bone metastasis in Ras-activated prostate cancer

Aberrant activation of Ras and WNT signaling are key events that have been shown to be up-regulated in prostate cancer that has metastasized to the bone. However, the regulatory mechanism of combinatorial Ras and WNT signaling in advanced prostate cancer is still unclear. TCF7, a WNT signaling-related gene, has been implicated as a critical factor in bone metastasis, and here we show that TCF7 is a direct target of miR-34a. In samples of prostate cancer patients, miR-34a levels are inversely correlated with TCF7 expression and a WNT dependent gene signature. Ectopic miR-34a expression inhibited bone metastasis and reduced cancer cell proliferation in a Ras-dependent xenograft model. We demonstrate that miR-34a can directly interfere with the gene expression of the anti-proliferative BIRC5, by targeting BIRC5 3′UTR. Importantly, BIRC5 overexpression was sufficient to reconstitute anti-apoptotic signaling in cells expressing high levels of miR-34a. In prostate cancer patients, we found that BIRC5 levels were positively correlated with a Ras signaling signature expression. Our data show that the bone metastasis and anti-apoptotic effects found in Ras signaling-activated prostate cancer cells require miR-34a deficiency, which in turn aids in cell survival by activating the WNT and anti-apoptotic signaling pathways thereby inducing TCF7 and BIRC5 expressions.

A secured authentication protocol for wireless sensor networks using elliptic curves cryptography

User authentication is a crucial service in wireless sensor networks (WSNs) that is becoming increasingly common in WSNs because wireless sensor nodes are typically deployed in an unattended environment, leaving them open to possible hostile network attack. Because wireless sensor nodes are limited in computing power, data storage and communication capabilities, any user authentication protocol must be designed to operate efficiently in a resource constrained environment. In this paper, we review several proposed WSN user authentication protocols, with a detailed review of the M.L Das protocol and a cryptanalysis of Das’ protocol that shows several security weaknesses. Furthermore, this paper proposes an ECC-based user authentication protocol that resolves these weaknesses. According to our analysis of security of the ECC-based protocol, it is suitable for applications with higher security requirements. Finally, we present a comparison of security, computation, and communication costs and performances for the proposed protocols. The ECC-based protocol is shown to be suitable for higher security WSNs.

Production, Purification, and Characterization of alpha-Galactosidase from Monascus pilosus

A Monascus pilosus strain was selected for production of intracellular alpha-galactosidase. Optimum conditions for mycelial growth and enzyme induction were determined. Galactose was one of the best enzyme inducers. The enzyme was purified by ammonium sulfate precipitation, gel filtration, and ion exchange chromatography and was demonstrated to be homogeneous by slab gel electrophoresis. The molecular weight of this enzyme, estimated by gel filtration, was about 150,000. The optimum conditions for the enzyme reaction was pH 4.5 to 5.0 at 55 degrees C. The purified enzyme was stable at 55 degrees C or below and in buffer at pH 3 to 8. The activity was inhibited by mercury, silver, and copper ions. The kinetics of this enzyme, with p-nitrophenyl-alpha-d-galactoside as substrate, was determined: K(m) was about 0.8 mM, and V(max) was 39 mumol/min per mg of protein. Enzymatic hydrolysis of melibiose, raffinose, and stachyose was analyzed by thin-layer chromatography.

A closed shell structured eyeball model with application to radial keratotomy

A closed shell structured eyeball model was developed for predicting the displacements and curvatures in an eyeball due to radial keratotomy. Both the cornea and sclera are modeled as an ellipsoidal cap, and the two caps are connected at the limbus to form a closed shell. The analysis of the number of corneal collagen laminae required for the tissue to be theoretically transversely isotropic was presented. The cornea, as well as the limbus and sclera, is considered as macroscopically homogeneous and isotropic in this study. A procedure to obtain the principal curvature at a point on the exterior surface was established. In the basic formulation, large displacements are contemplated. However, the FORTRAN computer program that was prepared to implement the procedure considers small displacements, and the resulting equations are linear. Although the results from this shell structured eyeball model are fairly good quantitatively, they do show vividly the following qualitative corneal behavior after the operation is performed: The opening of an incision has a V-shape, the radial displacements through the corneal thickness are nearly the same, and the largest in-plane displacement is only one-tenth of the largest radial displacement.

Detection and identification of toxigenic Vibrio cholerae O1 strains by a simplified polymerase chain reaction method

The polymerase chain reaction (PCR) with three oligonucleotide primers was used to amplify both 184 bp and 425 bp DNA fragments of cholera toxin A subunit gene (ctxA) for detection and identification of toxigenic V. cholerae O1 strains in one step. For enhancing the sensitivity, we have used the chemiluminescent detection system for Southern hybridization. A total of 92 Vibrio strains were tested by both PCR and enzyme-linked immunosorbent assay (ELISA). Three E. coli (ETEC) strains, one toxigenic V. mimicus, and one toxigenic V. cholerae non-O1 were also tested for cross reactivities. Our results indicated that the correlation between the immunological ELISA method and the molecular biological PCR method were very well. The lowest detectable amount of the purified serotype Inaba chromosomal DNA by PCR is 2 pg and 0.4 pg by chemiluminescent detection system. In this work we report a PCR assay with a combination of three primers to detect and identify the ctxA of V. cholerae O1 in one step. The simplified and accurate method is useful for toxigenic V. cholerae O1 detection and identification.

A unique mathematic model of the geometry of the human eyeball

The human eyeball was modeled as two intersecting ellipsoidal caps. Both the cornea and sclera were modeled as an ellipsoidal cap, and the two caps were connected at the limbus to form a completely closed shell. The shell coordinates and three Euler's angles were used, which uniquely defined the geometry of the eyeball. Computer programs were written to construct a geometric model of the human eyeball for radial keratotomy.

Phase analysis of gated blood pool scintigraphic images to localize bypass tracts in Wolff-Parkinson-White syndrome

The ability of radionuclide techniques to localize bypass tracts in patients with Wolff-Parkinson-White syndrome to sites around the atrioventricular (AV) ring using a three view triangulation method was investigated. In 17 patients with Wolff-Parkinson-White syndrome, phase images were generated from gated blood pool scans using the first Fourier harmonic of the time-activity curve of each pixel. In addition, the difference between left and right ventricular mean phase angles was calculated for each patient and for 13 control subjects. Bypass tracts were localized to one or more sites on a 10 site grid schematically superimposed on the AV ring (Duke grid) by electrophysiologic study in all patients and by intraoperative mapping in 7 of the 17 patients. These same 10 anatomic sites were projected onto three scintigraphic views and the site of earliest ventricular phase angle was located in each view. The 10 sites around the AV ring were divided into two anatomic groups: free wall and septal/paraseptal. Phase image locations correlated with electrophysiologic locations within one grid site in 11 of 11 patients with free wall tracts and were confirmed at surgery in 5 of the 11. In five of six patients with septal/paraseptal tracts, electrophysiologic study could not localize the bypass tract to one site, whereas phase images localized two of the five as free wall adjacent to the septum, one as paraseptal and two as true posteroseptal. One posteroseptal site was confirmed at surgery. In one patient, in whom phase image analysis and electrophysiologic study showed different sites, existence of both tracts was confirmed at surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence and clinical significance of the repetitive ventricular response during sinus rhythm in coronary disease patients

The prevalence of the repetitive ventricular response (RVR) after single and double premature stimulation during sinus rhythm or a paced supraventricular rhythm at a rate of 85 bpm was assessed in 343 patients (group 1: 237 patients studied prospectively who were referred for coronary arteriography and ventriculography; group 2: 44 patients after recent acute myocardial infarction; group 3: 61 patients with documented ventricular tachycardia and/or fibrillation). In group 1 patients, RVR testing was performed from both the right ventricular apex (n = 237) and outflow tract (n = 190), whereas in the remaining patients only the apex was stimulated. In group 1, RVR after a single premature stimulus occurred in 21.9% and after two stimuli in 63.2%. In patients with normal left ventricular (LV) function (n = 63) the prevalence of RVR after a single stimulus was significantly less (9.5%) than in those with LV dysfunction (n = 174;26.4%,p less than 0.01). However, after double stimulation, there was no longer any difference. In group 2, the prevalence of RVR was 25% after one and 34.1% after two premature stimuli. In group 3 patients, RVR was observed in only 14.8% after one and in 41% of patients after two premature stimuli. Ventricular tachycardia (greater than or equal to 10 QRS) was induced in nine patients during a supraventricular rhythm. Two hundred thirty-seven patients of group 1, who were prospectively studied in order to assess the prognostic significance of the RVR, were followed for a mean period of 27.2 +/- 10.7 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of antiarrhythmic surgery on late ventricular potentials recorded by precordial signal averaging in patients with ventricular tachycardia

In seven patients with documented ventricular tachycardia (VT) and prior myocardial infarction, late potentials (LP) were recorded at the end of or after the QRS complex from the body surface using high-gain amplification and the signal averaging technique (RC filter settings 100 to 300 Hz). In 6 to 7 patients VT could be initiated by programmed right ventricular stimulation; in one case, VT was inducible only from the left ventricle during surgery. Surgery was guided by epi- and endocardial mapping. In most cases besides resection of scar tissue, a partial or complete subendocardial encircling ventriculotomy was performed. Postoperatively, LPs were abolished in five cases, VT being no longer inducible. In the remaining two patients, LPs were still present. VT was still inducible in one of these two cases whereas in the other case, no programmed testing was done postoperatively. These data suggest that the abolition of LPs by surgery is closely related to the disappearance of the propensity to stimulus-induced VT. Thus, the averaging technique represents a new approach to the noninvasive control of the efficacy of surgery in patients with VT and prior myocardial infarction.

[Clinical-electrophysiological findings in patients following ventricular fibrillation]

30 patients, successfully resuscitated from ventricular fibrillation outside acute myocardial infarction, were studied by programmed right-ventricular stimulation. The stimulation studies were carried out one week up to 1.5 years after the event (median two months). Mean age of the patients was 50.2 +/- 8.8 years, 27 were male. The majority of patients had coronary heart disease and/or localized or diffuse ventricular contraction abnormalities. In 26 patients the stimulation protocol included the application of premature single and double ventricular stimuli during sinus rhythm and a paced ventricular rhythm at cycle lengths of 500, 430, 370 and 330 msec until ventricular tachycardia, ventricular flutter or ventricular fibrillation were induced. 4 patients were studied only at a cycle length of 500 msec. Using this stimulation protocol, in 7 patients (26.9%) sustained ventricular tachycardia, in 5 patients (19.2%) ventricular flutter and in 7 patients (26.9%) ventricular fibrillation were induced. These arrhythmias were induced at a basic cycle length of 500 ms in 10 patients, at 430 ms in 3 patients, at 370 ms in 4 patients and at 330 ms in 2 patients. In the remaining patients, only ventricular echo beats (one to six) of the intra-ventricular reentry type were induced. Thus these results show a persistent increase in ventricular vulnerability in a high percentage of patients (73%), provided that appropriate stimulation techniques are used. These observations may have great importance for the management of these patients.

[Response of ventricular late potentials after surgical therapy of ventricular tachycardia]

19 patients with either previously documented sustained ventricular tachycardia (VT) (n = 16) or only inducible VT (n = 3, one of whom had recurrent syncope), due to previous myocardial infarction were studied pre- and postoperatively. Mean age was 53 +/- 6 years, 16 were male, 3 female. In all but one, VT could be induced preoperatively by programmed right ventricular stimulation. Late potentials (LP) were recorded at the end of or after the QRS-complex from the body surface using high-gain amplification and the signal averaging technique (RC-filter settings 100 to 300 Hz). Indication for surgery was either intractable VT or bypass grafting and/or aneurysmectomy. Preoperatively, mean duration of late potentials was 54 +/- 37.7 ms, mean amplitude was 12 +/- 14.0 mean V. Surgery was guided by epi- and endocardial mapping. In 14 cases endomyocardial encircling ventriculotomy was the main procedure, whereas in 5 patients only aneurysmectomy and bypass grafting were performed. Postoperatively, late potentials were no longer detectable in 12 cases, whereas in 6 of 7 cases there was a decrease in duration, but no essential change in amplitude. A postoperative electrophysiological study was performed in 18 cases. In those 12 patients with abolition of LPs, the maximal number of inducible ventricular echo beats using an extended stimulation program from three right ventricular sites, ranged between 1 and 5 in 9 cases, between 10 and 11 VE in 2 cases, whereas VT was induced in only 1 case. In 6 patients in whom LPs were still detectable, ventricular tachycardia could still be induced in 2 cases and a maximal response of ten echo beats was observed in another patient. Abolition of LP by surgery is closely related to the disappearance of the propensity to stimulus-induced VT. Thus the averaging technique may provide a non-invasive procedure to assess the successful outcome after operation for ventricular tachycardia. If, however, LPs are still present, this does not exclude successful surgical abolition of the propensity to ventricular tachycardia.

Prevalence of late potentials in patients with and without ventricular tachycardia: correlation with angiographic findings

Late potentials occurring at the end of or after the QRS complex were searched for from the body surface using high gain amplification and signal averaging techniques with filter settings between 100 and 300 hertz. The number of repetitions of the averaging process ranged between 150 and 300. Two hundred thirty-six patients were studied. In 27 control subjects, no late potentials were recorded. Among 146 patients without ventricular tachycardia or fibrillation, late potentials were present in 49 (34 percent). The mean duration of late potentials was 31 +/- 15.3 ms (median 25). Of 63 patients with documented ventricular tachycardia or fibrillation, 45 (71 percent) had late potentials (mean duration 51 +/- 31.5 ms; median 50) (probability [p] greater than 0.001). There was a close correlation between the detection of late potentials and left ventricular function. Late potentials occurred more frequently in patients with than in those without ventricular akinesia or aneurysm and in patients with than in those without ventricular tachycardia or fibrillation. In conclusion, late potentials are a frequent finding in patients with regional contraction abnormalities, both in patients with and in those without documented ventricular tachycardia. The greater prevalence and longer duration of these signals in patients with ventricular tachycardia or fibrillation might be responsible for the greater susceptibility to ventricular tachycardia. Long-term follow-up studies will be necessary to assess the possible prognostic significance of late potentials in patients without previously documented ventricular tachycardia or fibrillation.

[Electrophysiological effects of flecainide on stimulus-inducible ventricular tachycardia]

13 patients (54 +/- 11.8 years) with either spontaneously occurring ventricular tachycardia (N = 12) or recurrent syncope (n = 1) probably due to ventricular tachycardia were studied electrophysiologically. In all patients, ventricular tachycardia could be initiated by programmed right ventricular stimulation during the control study. Ventricular tachycardia was sustained in eleven patients and non-sustained in the remaining two. After several days of oral administration of flecainide (400 to 500 mg per day) sustained ventricular tachycardia could still be initiated in seven cases that had to be interrupted by overdrive stimulation in five cases, and by cardioversion in the remaining two. In six cases, short, self-terminating episodes of ventricular tachycardia were induced. In four patients, induction of ventricular tachycardia was unchanged or made easier, whereas in seven cases ventricular tachycardia was more difficult to induce (i.e. later during the step-like stimulation program). The mean rate of induced ventricular tachycardia decreased from 215 +/- 59.4/min (+/- S.D.) to 169 +/- 44.1/min during flecainide (p less than 0.025). The interval between the tachycardia-initiating beat and the first beat of tachycardia increased from 323 +/- 61.1 ms to 438 +/-148.3 ms (P less than 0.02). The effective refractory period of the right ventricle was prolonged from 240 +/- 20.5 ms t 279 +/- 37.3 ms (P less than 0.005). The plasma concentration of flecainide at the time of stimulation was 995 +/- 238 ng/ml. Thus, flecainide exerts a marked effect on the rate of induced ventricular tachycardia, whereas the mode of induction did not change considerably. The prophylactic effect of long-term therapy with flecainide in patients with recurrent ventricular tachycardia needs further studies.

[Electrophysiological findings and follow-up in patients with syncope (author's transl)]

92 patients (mean age 54 +/- 14.7 years, 54 men) with unexplained syncopes were investigated by Holter monitoring, exercise testing and His-bundle-electrography (high-rate and programmed atrial stimulation). The diagnoses on 43 patients were sinus node dysfunction, in 32 cases atrio and/or intraventricular block, and in 6 patients idiopathic atrial fibrillation, whereas 8 patients had a history of ventricular tachycardia, 48 patients received a pacemaker (mean age 58 +/- 12.9 years), and 44 patients were discharged without a pacemaker (mean age 49 +2- 15.6 years). The mean duration of follow-up was 56 +2- 17.1 months. There were 13 deaths, 9 patients died from heart failure, 1 died suddenly, and 3 patients died from non-cardiac causes. 7 patients were lost to follow-up. 54 patients had no syncope any longer, while in 18 cases syncope was still present, 14 patients without pacemaker and 4 patients with pacemaker still had attacks. The cardiac mortality was 18.8% (with pacemaker) and 2.3% (without pacemaker). The only sudden cardiac death was observed in a patient with pacemaker. This study shows that pacemaker implantation bases on electrophysiologic study is able to improve symptoms in patients with syncope. However, the long-term prognosis of the patients is mainly depending on the severity of their underlying heart disease.

The effects of treatment with antibiotics, laser and acupuncture upon chronic maxillary sinusitis in children

In a clinical study we compared three different types of therapy in chronic maxillary sinusitis. 45 patients, 3-40 years old, were treated, 19 with antibiotics, 18 with acupuncture and 8 with Laser-acupuncture. There was no statistical difference of results between Laser-therapy and antibiotics (Chi-Square-Test). Compared to previous treatments with antibiotics, results and duration of improvement was significantly better after acupuncture.

CONCLUSION

acute sinusitis, especially of frontal sinus and in younger children, will better be treated by antibiotics because of the danger of osteomyelitis and meningitis. Acupuncture should be tried in chronic and recurrent stages after exclusion of large adenoids in children or bone inhibition of sinus clearance, especially before an invasive operation like removal of sinus mucosa is carried out.