Cartilage oligomeric matrix protein promotes prostate cancer progression by enhancing invasion and disrupting intracellular calcium homeostasis

Cartilage oligomeric matrix protein (COMP) was recently implicated in the progression of breast cancer. Immunostaining of 342 prostate cancer specimens in tissue microarrays showed that COMP expression is not breast cancer-specific but also occurs in prostate cancer. The expression of COMP in prostate cancer cells correlated with a more aggressive disease with faster recurrence. Subcutaneous xenografts in immunodeficient mice showed that the prostate cancer cell line DU145 overexpressing COMP formed larger tumors in vivo as compared to mock-transfected cells. Purified COMP bound to and enhanced the invasion of DU145 cells in vitro in an integrin-dependent manner. In addition, intracellular COMP expression interfered with cellular metabolism by causing a decreased level of oxidative phosphorylation with a concurrent upregulation of lactate production (Warburg effect). Further, expression of COMP protected cells from induction of apoptosis via several pathways. The effect of COMP on metabolism and apoptosis induction was dependent on the ability of COMP to disrupt intracellular Ca²⁺ signalling by preventing Ca²⁺ release from the endoplasmic reticulum. In conclusion, COMP is a potent driver of the progression of prostate cancer, acting in an anti-apoptotic fashion by interfering with the Ca²⁺ homeostasis of cancer cells.

Quantitative Time-Resolved Fluorescence Imaging of Androgen Receptor and Prostate-Specific Antigen in Prostate Tissue Sections

Androgen receptor (AR) and prostate-specific antigen (PSA) are expressed in the prostate and are involved in prostate cancer (PCa). The aim of this study was to develop reliable protocols for reproducible quantification of AR and PSA in benign and malignant prostate tissue using time-resolved fluorescence (TRF) imaging techniques. AR and PSA were detected with TRF in tissue microarrays from 91 PCa patients. p63/ alpha-methylacyl-CoA racemase (AMACR) staining on consecutive sections was used to categorize tissue areas as benign or cancerous. Automated image analysis was used to quantify staining intensity. AR intensity was significantly higher in AMACR+ and lower in AMACR- cancer areas as compared with benign epithelium. The PSA intensity was significantly lower in cancer areas, particularly in AMACR- glands. The AR/PSA ratio varied significantly in the AMACR+ tumor cells as compared with benign glands. There was a trend of more rapid disease progression in patients with higher AR/PSA ratios in the AMACR- areas. This study demonstrates the feasibility of developing reproducible protocols for TRF imaging and automated image analysis to study the expression of AR and PSA in benign and malignant prostate. It also highlighted the differences in AR and PSA protein expression within AMACR- and AMACR+ cancer regions.

REST mediates androgen receptor actions on gene repression and predicts early recurrence of prostate cancer

The androgen receptor (AR) is a key regulator of prostate tumorgenesis through actions that are not fully understood. We identified the repressor element (RE)-1 silencing transcription factor (REST) as a mediator of AR actions on gene repression. Chromatin immunoprecipitation showed that AR binds chromatin regions containing well-characterized cis-elements known to mediate REST transcriptional repression, while cell imaging studies confirmed that REST and AR closely co-localize in vivo. Androgen-induced gene repression also involves modulation of REST protein turnover through actions on the ubiquitin ligase β-TRCP. Androgen deprivation or AR blockage with inhibitor MDV3100 (Enzalutamide) leads to neuroendocrine (NE) differentiation, a phenomenon that is mimicked by REST inactivation. Gene expression profiling revealed that REST not only acts to repress neuronal genes but also genes involved in cell cycle progression, including Aurora Kinase A, that has previously been implicated in the growth of NE-like castration-resistant tumors. The analysis of prostate cancer tissue microarrays revealed that tumors with reduced expression of REST have higher probability of early recurrence, independently of their Gleason score. The demonstration that REST modulates AR actions in prostate epithelia and that REST expression is negatively correlated with disease recurrence after prostatectomy, invite a deeper characterization of its role in prostate carcinogenesis.

Carbon monoxide expedites metabolic exhaustion to inhibit tumor growth

One classical feature of cancer cells is their metabolic acquisition of a highly glycolytic phenotype. Carbon monoxide (CO), one of the products of the cytoprotective molecule heme oxygenase-1 (HO-1) in cancer cells, has been implicated in carcinogenesis and therapeutic resistance. However, the functional contributions of CO and HO-1 to these processes are poorly defined. In human prostate cancers, we found that HO-1 was nuclear localized in malignant cells, with low enzymatic activity in moderately differentiated tumors correlating with relatively worse clinical outcomes. Exposure to CO sensitized prostate cancer cells but not normal cells to chemotherapy, with growth arrest and apoptosis induced in vivo in part through mitotic catastrophe. CO targeted mitochondria activity in cancer cells as evidenced by higher oxygen consumption, free radical generation, and mitochondrial collapse. Collectively, our findings indicated that CO transiently induces an anti-Warburg effect by rapidly fueling cancer cell bioenergetics, ultimately resulting in metabolic exhaustion.

Automatic registration of multi-modal microscopy images for integrative analysis of prostate tissue sections

Background

Prostate cancer is one of the leading causes of cancer related deaths. For diagnosis, predicting the outcome of the disease, and for assessing potential new biomarkers, pathologists and researchers routinely analyze histological samples. Morphological and molecular information may be integrated by aligning microscopic histological images in a multiplex fashion. This process is usually time-consuming and results in intra- and inter-user variability. The aim of this study is to investigate the feasibility of using modern image analysis methods for automated alignment of microscopic images from differently stained adjacent paraffin sections from prostatic tissue specimens.

Methods

Tissue samples, obtained from biopsy or radical prostatectomy, were sectioned and stained with either hematoxylin & eosin (H&E), immunohistochemistry for p63 and AMACR or Time Resolved Fluorescence (TRF) for androgen receptor (AR).

Image pairs were aligned allowing for translation, rotation and scaling. The registration was performed automatically by first detecting landmarks in both images, using the scale invariant image transform (SIFT), followed by the well-known RANSAC protocol for finding point correspondences and finally aligned by Procrustes fit. The Registration results were evaluated using both visual and quantitative criteria as defined in the text.

Results

Three experiments were carried out. First, images of consecutive tissue sections stained with H&E and p63/AMACR were successfully aligned in 85 of 88 cases (96.6%). The failures occurred in 3 out of 13 cores with highly aggressive cancer (Gleason score ≥ 8). Second, TRF and H&E image pairs were aligned correctly in 103 out of 106 cases (97%).

The third experiment considered the alignment of image pairs with the same staining (H&E) coming from a stack of 4 sections. The success rate for alignment dropped from 93.8% in adjacent sections to 22% for sections furthest away.

Conclusions

The proposed method is both reliable and fast and therefore well suited for automatic segmentation and analysis of specific areas of interest, combining morphological information with protein expression data from three consecutive tissue sections. Finally, the performance of the algorithm seems to be largely unaffected by the Gleason grade of the prostate tissue samples examined, at least up to Gleason score 7.

The lysine specific demethylase-1 (LSD1/KDM1A) regulates VEGF-A expression in prostate cancer

Recurrent prostate cancer remains a major clinical challenge. The lysine specific demethylase-1 (LSD1/KDM1A), together with the JmjC domain-containing JMJD2A and JMJD2C proteins, have emerged as critical regulators of histone lysine methylation. The LSD1-JMJD2 complex functions as a transcriptional co-regulator of hormone activated androgen and estrogen receptors at specific gene promoters. LSD1 also regulates DNA methylation and p53 function. LSD1 is overexpressed in numerous cancers including prostate cancer through an unknown mechanism. We investigated expression of the LSD1 and JMJD2A in malignant human prostate specimens. We correlated LSD1 and JMJD2A expression with known mediators of prostate cancer progression: VEGF-A and cyclin A1. We show that elevated expression of LSD1, but not JMJD2A, correlates with prostate cancer recurrence and with increased VEGF-A expression. We show that functional depletion of LSD1 expression using siRNA in prostate cancer cells decreases VEGF-A and blocks androgen induced VEGF-A, PSA and Tmprss2 expression. We demonstrate that pharmacological inhibition of LSD1 reduces proliferation of both androgen dependent (LnCaP) and independent cell lines (LnCaP: C42, PC3). We show a direct mechanistic link between LSD1 over-expression and increased activity of pro-angiogenic pathways. New therapies targeting LSD1 activity should be useful in the treatment of hormone dependent and independent prostate cancer.

Emphasizing the role of Wnt5a protein expression to predict favorable outcome after radical prostatectomy in patients with low-grade prostate cancer

Wnt5a, a member of non-canonical wingless-related MMTV integration site family is a secreted glycoprotein that plays important roles in development and disease. Recent studies have shown that Wnt5a protein levels are up-regulated in prostate cancer, but contrasting reports exist on the role of Wnt5a to predict outcome after radical prostatectomy in patients with localized prostate cancer. Our group has recently shown that preserved high protein expression of Wnt5a in prostate cancer is associated with longer relapse-free time after radical prostatectomy. The present tissue microarray study emphasizes the role of Wnt5a protein expression in a different, well-defined, and independent cohort consisting of 312 prostate cancer patients. Kaplan–Meier curves plotted between Wnt5a expression and time to biochemical recurrence revealed that in low-grade prostate cancer, patients with preserved high-Wnt5a protein levels in their tumor cells have a lower risk of recurrence after radical prostatectomy compared to patients with low-Wnt5a protein expression. When Wnt5a protein expression was added to a Cox regression multivariate analysis, both Wnt5a protein expression and surgical margin status independently predict biochemical free survival. Herein we confirm Wnt5a positivity as a prognostic factor and show that preserved overexpression of Wnt5a protein is associated with increased time to biochemical recurrence in localized low-grade prostate cancer patients after radical prostatectomy. Our results emphasize that Wnt5a can be used as a predictive biomarker, and favoring the view of Wnt5a as a future therapeutic target in prostate cancer patients with tumor cells displaying low expression of Wnt5a.

Abstract LB-358: Heme oxygenase-1 and carbon monoxide arrest tumor growth via modulation of cellular respiration

Heme oxygenase-1 (HO-1) and carbon monoxide (CO) are endogenous cytoprotective molecules yet their role in tumor growth, metastasis, cell death and DNA damage has not been elucidated. HO-1 expression was assessed in prostate cancer biopsies from 482 patients and strong nuclear staining, indicative of loss of enzymatic activity was observed in moderately differentiated tumors. Employing prostate cancer (PCa) as our model we treated PCa cells with the chemotherapeutics camptothecin or doxorubicin and observed an increase in cytosolic HO-1 activity that correlated with increased cell death. Overexpression of HO-1 or exogenous pretreatment with CO increased tumor cell sensitivity to chemotherapeutics one thousand fold. In contrast, CO blocked chemotherapeutic-induced cell death of normal prostate epithelial cells. In vivo, CO exposure of mice with established PC3 xenografts resulted in complete growth arrest and sensitization of tumors to doxorubicin with mitotic blockade and enhanced apoptosis of the tumor cells. Exposure to CO showed similar effects in a model of PC3 orthotopic tumors with significant inhibition in markers of invasion. Further, CO blocked development of PIN and prostate tumors in the model of TRAMP mice with concomitant targeting of mitochondria. Further, CO inhibited growth of lung adenocarcinoma in the inducible KRas model of carcinogenesis. Collectively, our data demonstrate the importance of cellular localization of HO-1 in human PCa progression and importantly that CO in part, regulates cellular sensitivity to DNA damaging agents and offers a novel therapeutic adjuvant for the treatment of cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-358. doi:1538-7445.AM2012-LB-358

Elevated level of Wnt5a protein in localized prostate cancer tissue is associated with better outcome

BACKGROUND

Wnt5a is a non-canonical secreted glycoprotein of the Wnt family that plays an important role in cancer development and progression. Previous studies report that Wnt5a is upregulated in prostate cancer and suggested that Wnt5a affects migration and invasion of prostate tumor cell. This study aimed to evaluate the prognostic value of Wnt5a protein expression in prostate cancer tissue and its potential to predict outcome after radical prostatectomy in patients with localized prostate cancer.

METHODOLOGY AND RESULTS

Immunohistochemical analysis of a tissue microarray containing prostate specimens of 503 patients with localized prostate cancer showed significantly higher Wnt5a protein expression in cancer compared to benign cores from the same patients (p<0.0001). Patients with high expression of Wnt5a protein had significantly better outcome in terms of time to biochemical recurrence compared to patients with low expression levels (p = 0.001, 95%CI 1.361-3.570, Hazard's ratio 2.204). A combination of high Wnt5a expression with low levels of Ki-67 or androgen receptor expression had even better outcome compared to all other groups. Furthermore, we found that Wnt5a expression significantly correlated with VEGF and with Ki-67 and androgen receptor expression, although not highly significant. In vitro, we demonstrated that recombinant Wnt5a decreased invasion of 22Rv1 and DU145 cells and that siRNA knockdown of endogenous Wnt5a protein led to increased invasion of 22Rv1 and LNCaP cells.

CONCLUSION

We demonstrate that preserved overexpression of Wnt5a protein in patients with localized prostate cancer predicts a favorable outcome after surgery. This finding together with our in vitro data demonstrating the ability of Wnt5a to impair the invasive properties of prostate cancer cells, suggests a tumor suppressing effect of Wnt5a in localized prostate cancer. These results indicate that Wnt5a can be used as a predictive marker and that it also is a plausible therapeutic target for treatment of localized prostate cancer.

Abstract C41: Heme oxygenase-1 and carbon monoxide modulate responses to DNA damage in prostate cancer

Heme oxygenase (HO) and carbon monoxide (CO), a product of HO activity generated during heme catalysis, exert differential effects on the apoptotic response dependently on the environmental milieu and cell types involved. The role of HO-1 and CO in modulating chemotherapeutic treatment in prostate cancer has not been tested. Our focus in this work explored the role of HO-1 and CO in modulating PCa cell death via DNA damage mechanisms. We examined HO-1 expression in PCa samples from 482 patients and found strong nuclear staining in moderately differentiated tumors (Gleason grade 3). Treatment of PCa cells with the chemotherapeutic agents, camptothecin or doxorubicin increased HO-1 activity in the cytosol, which correlated with increased cell death. Nuclear translocation of HO-1 resulted in decreased enzymatic activity. Low activity of HO-1 in the nucleus may confer resistance to chemotherapy due to the antiapoptotic effects of HO-1. Overexpression of cytosolic and active HO-1 or exogenous delivery of CO at low non-toxic concentrations (250 parts per million) in combination with a chemotherapeutic led to enhanced tumor cell death via caspase-3 activation. CO exposure of mice with established PC3 xenografts delayed tumor growth via accelerated apoptosis (TUNEL staining) and mitotic catastrophe of cancer cells as well as strong inhibition of angiogenesis (CD31 staining). Further, CO sensitized tumors to doxorubicin treatment with enhanced apoptosis and blockage of mitosis. In contrast, CO blocked chemotherapeutic-induced cell death in normal cells supporting a new function for HO-1/CO as cellular sensors of DNA damage. Taken together, our data demonstrate the importance of cellular localization of HO-1 in PCa progression and importantly that CO, in part regulates cellular sensitivity to DNA damaging agents. We propose a novel strategy to overcome resistance to chemotherapy as well as reducing the chemotherapeutic burden by employing CO at safe, non-toxic concentrations that permits preservation of normal cells and tissue.

Citation Information: Cancer Res 2009;69(23 Suppl):C41.

Cystatin C is downregulated in prostate cancer and modulates invasion of prostate cancer cells via MAPK/Erk and androgen receptor pathways

Cystatin C is believed to prevent tumor progression by inhibiting the activities of a family of lysosomal cysteine proteases. However, little is known about the precise mechanism of cystatin C function in prostate cancer. In the present study, we examined the expression of cystatin C and its association with matrix metalloproteinases 2 (MMP2) and androgen receptor (AR) in a tissue microarray comparing benign and malignant specimens from 448 patients who underwent radical prostatectomy for localized prostate cancer. Cystatin C expression was significantly lower in cancer specimens than in benign tissues (p<0.001) and there was a statistically significant inverse correlation between expression of cystatin C and MMP2 (r_s² = −0.056, p = 0.05). There was a clear trend that patients with decreased level of cystatin C had lower overall survival. Targeted inhibition of cystatin C using specific siRNA resulted in an increased invasiveness of PC3 cells, whereas induction of cystatin C overexpression greatly reduced invasion rate of PC3 in vitro. The effect of cystatin C on modulating the PC3 cell invasion was provoked by Erk2 inhibitor that specifically inhibited MAPK/Erk2 activity. This suggests that cystatin C may mediate tumor cell invasion by modulating the activity of MAPK/Erk cascades. Consistent with our immunohistochemical findings that patients with low expression of cystatin C and high expression of androgen receptor (AR) tend to have worse overall survival than patients with high expression of cystatin C and high AR expression, induced overexpression of AR in PC3 cells expressing cystatin C siRNA greatly enhanced the invasiveness of PC3 cells. This suggests that there may be a crosstalk between cystatin C and AR-mediated pathways. Our study uncovers a novel role for cystatin C and its associated cellular pathways in prostate cancer invasion and metastasis.

Tubulointerstitial Renal Diseases of Children: Pathologic Features and Pathogenetic Mechanisms in Fanconi's Familial Nephronophthisis, Antitubular Basement Membrane Antibody Disease, and Medullary Cyst Disease

The renal lesions of 15 children with tubulointerstitial diseases (TID), originally diagnosed as Fanconi's familial nephronophthisis (FFN), medullary cyst disease (MCD), or antitubular basement membrane (TBM) antibody disease were studied by light, electron, and immunofluorescence microscopy and by peroxidase-antiperoxidase stain for IgG. Kidneys originally considered in all three categories showed similar pathologic findings, with periglomerular fibrosis, interstitial fibrosis and infiltration, TBM thickening, and glomerulopathy. The data suggest that MCD and FFN are not synonyms, but that FFN can lead to medullary cystic disease, as can other tubulointerstitial diseases. Anti-TBM disease appears to be a more frequent cause of TID than is usually recognized. Glomerular involvement in TID may be due to deposition of anti-TBM antibody/TBM antigen complexes.

Multiple cellular mechanisms related to cyclin A1 in prostate cancer invasion and metastasis

BACKGROUND

Cyclin A1 is a cell cycle regulator that has been implicated in the progression of prostate cancer. Its role in invasion and metastasis of this disease has not been characterized.

METHODS

Immunohistochemistry and cDNA microarray analyses were used to assess protein and mRNA expression of cyclin A1 and proteins with roles in metastasis, including vascular endothelial growth factor (VEGF), metalloproteinase 2 (MMP2), and MMP9, in human prostate cancer. Transient transfection and infection with viral vectors expressing cyclin A1 and short hairpin RNA (shRNA) targeting cyclin A1 were used to study the effects of altered cyclin A1 expression in PC3 prostate cancer cells. The BrdU assay, annexin V staining, and invasion chambers were used to examine cyclin A1 effects on proliferation, apoptosis, and invasion, respectively. The role of cyclin A1 and androgen receptor (AR) in transcription of VEGF and MMP2 was assessed by promoter mutation and chromatin immunoprecipitation. The effect of cyclin A1 expression on tumor growth and metastasis was analyzed in a mouse model of metastasis. All statistical tests were two-sided.

RESULTS

Cyclin A1 protein and mRNA expression were statistically significantly higher in prostate cancers than in adjacent benign tissues. A statistically significant correlation between expression of cyclin A1 and of MMP2, MMP9, and VEGF was observed in prostate tumors from 482 patients (P values from Spearman rank correlation tests < .001). PC3 cells that overexpressed cyclin A1 showed increased invasiveness, and inhibition of cyclin A1 expression via shRNA expression reduced invasiveness of these cells. Eight of 10 mice (80%) bearing PC3 cells overexpressing cyclin A1 had infiltration of tumor cells in lymph node, liver, and lung, but all 10 mice bearing tumors expressing control vector were free of liver and lung metastases and only one mouse from this group had lymph node metastasis (P values from Fisher exact tests < .001). Cyclin A1, in concert with AR, bound to and increased expression from the VEGF and MMP2 promoters.

CONCLUSIONS

Cyclin A1 contributes to prostate cancer invasion by modulating the expression of MMPs and VEGF and by interacting with AR.

Delta-like 1 (Dlk-1), a novel marker of prostate basal and candidate epithelial stem cells, is downregulated by notch signalling in intermediate/transit amplifying cells of the human prostate

BACKGROUND

There is a lack of understanding of the processes that regulate differentiation in the prostate.

OBJECTIVE

To determine localisation, activity, and regulation of cytodifferentiation-modulatory proteins in the human adult prostate.

DESIGN, SETTINGS, AND PARTICIPANTS

Eighteen volunteering patients with organ-confined prostate cancer were prospectively enrolled at a single university hospital.

INTERVENTION

All patients underwent radical prostatectomy, and normal/benign tissue was excised and obtained from the transition zone.

MEASUREMENTS

Expression and activity of Notch-protein family members, including the Notch-homologous protein Delta-like 1 (Dlk-1/Pref1), were investigated immunohistochemically in normal/benign tissue and explant cultures. The effect of the Notch inhibitor L-685,458 on Dlk-1 expression and cell number was investigated in primary cell cultures, and data were analysed with Student t test.

RESULTS AND LIMITATIONS

Mature luminal cells were found to co-express Notch-1 and its ligand Jagged1, but epithelia in normal/benign tissue showed no active Notch signalling. The basal cell layer, rare candidate epithelial stem cells, and a subpopulation of neuroendocrine cells expressed the differentiation protein Dlk-1. In explant cultures, luminal cells and Jagged1 expression were lost, whereas intermediate cells downregulated Dlk-1 concomitant with Notch-1 upregulation and activation. Notch inhibition in primary cell cultures led to lower cell densities (p<0.001) and suppressed downregulation of Dlk-1. This is a small study; current results need to be confirmed in larger investigations.

CONCLUSIONS

We demonstrate that Notch-1 is upregulated in differentiation of prostate epithelia, and that the novel prostate progenitor marker Dlk-1 is downregulated by Notch signalling in intermediate cells. The identification of Dlk-1-expressing candidate stem and neuroendocrine cells suggests a hierarchical relationship.

Localization of immunoreactive HIF-1alpha and HIF-2alpha in neuroendocrine cells of both benign and malignant prostate glands

BACKGROUND

Hypoxia induces increased tumor growth by promoting angiogenic and glycolytic pathways. Tumors expressing hypoxia-inducible factor-1alpha (HIF-1alpha), an important transcriptional activator of oxygen-regulated genes, are resistant to chemotherapy and radiotherapy. The major challenge in prostate cancer therapy today is to gain a better understanding of the development of hormone-refractory tumors, which is often characterized by neuroendocrine differentiation. Here we studied the expression of HIF-1alpha and HIF-2alpha in neuroendocrine cells of the benign prostate and in prostate cancer.

METHODS

Tissue sections from 30 patients who underwent radical prostatectomy and from 21 patients operated by transurethral resection of the prostate were selected for immunohistochemical analysis for expression of HIF-1alpha, HIF-2alpha, androgen receptor (AR), neuroendocrine markers (chromogranin A, synaptophysin), and two gene products downstream of HIF-1alpha: VEGF and GAPDH.

RESULTS

Immunoreactive HIF-1alpha was detected in a subpopulation of AR-negative neuroendocrine cells in benign and malignant prostate tissue. Analysis of serial sections showed that the levels of expression of GAPDH and VEGF proteins are increased in AR-negative malignant neuroendocrine cells expressing HIF-1alpha. In situ-hybridization indicated that HIF-1alpha mRNA levels are not higher in neuroendocrine prostate cancer cells relative to corresponding non-neuroendocrine tumor cells. We also demonstrated induced stabilization of nuclear HIF-1alpha in LNCaP cells by hypoxia and long-term stimulation with interleukin-6. Focal HIF-2 expression was detected in benign neuroendocrine-like cells and in malignant prostatic cells.

CONCLUSIONS

The expression of HIF-1alpha and HIF-2alpha in prostate cancer has been confirmed, but we also identified immunoreactive HIF-1alpha and downstream gene products in benign and malignant prostate neuroendocrine cells.

Influence of higher-order dispersion on modulational instability and pulse broadening of partially incoherent light

The Wigner-Moyal equation for the Wigner distribution of a partially incoherent optical wave field propagating in dispersive and nonlinear media has been generalized to include the effects of both arbitrary order of dispersion and arbitrary nonlinearity. The theory predicts partial incoherence to enhance the pulse broadening during linear wave pulse propagation. Furthermore, an application of the theory to the modulational instability of constant amplitude waves shows how higher-order dispersion affects the instability growth rate.

Eigenvalues of the Zakharov-Shabat scattering problem for real symmetric pulses

The classical problem of determining the solitons generated from symmetric real initial conditions in the nonlinear Schrödinger equation is revisited. The corresponding Zakharov-Shabat scattering problem is solved for real and symmetric double-humped rectangular initial pulse forms. It is found that such real symmetric pulses may generate eigenvalues with nonzero real parts corresponding to separating soliton pulse pairs. Moreover, it is found that the classical formula relating the number of eigenvalues to the area of the pulse is not always correct.

Propagation properties of chirped soliton pulses in optical nonlinear Kerr media

An investigation is made of the formation of a single soliton, or a pair of solitons, from initially nontransform limited pulses in a nonlinear Kerr medium having anomalous dispersion. A qualitative physical explanation is given for the formation of soliton pairs. Approximate solutions for the amplitudes and the velocities of the generated solitons are established and corroborated by numerical solutions of the Zakharov-Shabat eigenvalue problem.

The renal lesion of congenital hepatic fibrosis: pathologic and morphometric analysis, with comparison to the renal lesion of infantile polycystic disease

The renal lesion of congenital hepatic fibrosis (CHF = Blyth and Ockenden's juvenile polycystic disease of liver and kidneys) was analyzed from 6 specimens from patients aged 3 3/12 to 19 3/12 years and compared with that of 5 patients with infantile polycystic disease (IPCD) aged 6 months to 14 4/12 years. Pathologic, microdissection, injection, and morphometric studies show that the predominantly medullary cystic lesion of CHF shows different distribution in medullary, cortico-medullary, and cortical zones of kidney from the lesion of IPCD, and shows a different time course, from early life to renal insufficiency, from that of IPCD. The renal cysts in CHF affect deep or central collecting tubules, in contrast to the involvement of more peripheral orders of collecting tubules in IPCD. Papillary pore counts, performed for 1 patient, gave significantly low values, in contrast to normal values reported for IPCD. The findings support the previously published conclusion, based on differences in the hepatic lesions of the two conditions, that CHF and IPCD are difference diseases, rather than different permissible manifestations of a single disease.