Clinicopathologic Features of Prostate Cancer with Mesorectal Lymph Node Involvement on PSMA or Fluciclovine PET/CT

PURPOSE/OBJECTIVE(S)

Advanced PET imaging has shown more prevalent mesorectal lymph node (LN) involvement in prostate cancer than previously appreciated. The clinical features predicting risk for mesorectal involvement are not well established and the prognostic impact is unclear. This may have implications on management including radiotherapy field design. This study aims to identify clinical and pathologic characteristics associated with mesorectal involvement identified on PSMA or fluciclovine PET/CT.

MATERIALS/METHODS

We conducted a single institution retrospective review of prostate cancer patients with F-18 fluciclovine, F-18 piflufolastat, or Ga-68 gozetotide PET between January 2020 and 2023 demonstrating tracer-avid mesorectal LN in the setting of newly diagnosed disease (ND) or biochemical failure after curative-intent therapy (BF). Clinical characteristics, pathologic findings, and early clinical outcomes were reviewed.

RESULTS

We identified 16 ND and 34 BF patients with uptake in at least one mesorectal LN on PET. For ND patients, clinical features at initial diagnosis were median PSA of 35.2 (range 9.6-659), median grade group 5, and 87% with clinical or radiographic T3/T4 disease. Radiographic PET staging among ND patients (excluding mesorectal LNs) were 19% N0M0, 25% N1M0, 56% as N1M1. For BF patients, clinical features at initial diagnosis were median PSA 9.2 (range 4.1-90) and median grade group 4. Primary treatment was prostatectomy in most (91%), with a high rate of high-risk features: 68% pT3-4, 28% pN1, and 32% had persistent detectable postop PSA. Radiographic PET staging among BF patients (excluding mesorectal LNs) were 29% N0M0, 38% N1M0, 12% N0M1, and 21% as N1M1. High-risk histologic features (cribriform, intraductal, ductal, or neuroendocrine) were identified in 88% of ND and 48% BF patients. Of these patients, 86% had cribriform pattern. Median PSA prior to PET for ND and BF patients was 37.0 (range 8.5-659) and 1.9 (0.2-11.1). Median interval from initial therapy to PET for BF patients was 4.4yr (range 0.2-19.7). Median follow-up post-PET was 8.7mo (range 3.4-29) for ND and 8.8mo (range 0-76) for BF patients. Of patients with M0 PET staging, none of the 7 ND patients developed DMs, and 1 of 23 BF patients developed DM after 4 yrs.

CONCLUSION

In this analysis of prostate cancer patients with mesorectal involvement, we found a high incidence of high grade, T3-4 disease, and cribriform pattern, especially in ND patients. For BF patients, there was a high incidence of pT3-4 and pN1 disease at time of initial treatment. Overall, most patients had concurrent regional nodal disease on PET. Longer follow up of clinical outcomes and comparison to high-risk patients without mesorectal LN involvement is needed to understand the prognostic significance and predictors of mesorectal LN spread. Additional studies are needed to identify patients at highest risk in whom elective coverage of mesorectal lymphatics with elective pelvic nodal RT may be warranted.

Cross-Platform in-silico Analyses Exploring Tumor Immune Microenvironment with Prognostic Value in Triple-Negative Breast Cancer

INTRODUCTION

Only a proportion of triple-negative breast cancer (TNBC) is immunotherapy-responsive. We hypothesized that the tumor microenvironment (TME) influences the outcomes of TNBC and investigated the relevant signaling pathways.

MATERIALS AND METHODS

Immune score (IS) and stromal score (SS) were calculated using the ESTIMATE and correlated with the overall survival (OS) in TNBC. RNA-seq data from 115 TNBC samples and 112 normal adjacent tissues were retrieved. Validations in the methylation levels in 10 TNBC and five non-TNBC cell lines were obtained. Cox model overall survival (OS) validated the derived transcription factor (TF) genes in cBioPortal breast cancer patients.

RESULTS

SS-low predicts a higher OS compared with SS-high patients (P = 0.0081 IS-high/SS-low patients had better OS (P = 0.045) than IS-low/SS-high patients. More macrophages were polarized to the M2 state in patients with IS-low/SS-high patients (P < 0.001). Moreover, CIBERSORTx showed more CD8+ cytotoxic T-cells in IS-high/SS-low patients (p = 0.0286) and more resting NK cells in the IS-low/SS-high TME (P = 0.0108). KEGG pathway analysis revealed that overexpressed genes were enriched in the IL-17 and cytokine-cytokine receptor interaction pathways. The lncRNA DRAIC, a tumor suppressor, was consistently deactivated in the 10 TNBC cell lines. On the cBioPortal platform, we validated that 13% of ER-negative, HER2-unamplified BC harbored IL17RA deep deletion and 25% harbored TRAF3IP2 amplification. On cBioPortal datasets, the nine altered TF genes derived from the X2K analysis showed significantly worse relapse-free survival in 2377 patients and OS in 4819 invasive BC patients than in the unaltered cohort.

CONCLUSION

Of note, the results of this integrated in silico study can only be generalized to approximately 17% of patients with TNBC, in which infiltrating stromal cells and immune cells play a determinant prognostic role.

[Effect of peritoneum reconstruction on postoperative complications after laparoscopic low anterior resection for rectal cancer]

Objective: To determine the effect of peritoneum reconstruction on postoperative complications after laparoscopic low anterior resection (LAR) for rectal cancer. Methods: Retrospective cohort study and propensity score matching were conducted. Case inclusion criteria: (1) pathologically confirmed rectal adenocarcinoma; (2) 18 to 80 years; (3) patients with middle to low rectal cancer undergoing laparoscopic LAR; (4) patients staging cT1-4aN0-2M0 or ycT1-4aN0-2M0 after neoadjuvant therapy; (5) the distance of 4-10 cm from tumor low margin to anal verge. Exclusion criteria: (1) abdominal surgery history (except appendicitis, cholecystitis, ectopic pregnancy); (2) anastomosis above the peritoneal reflection; (3) tumor distant metastasis or clinical staging of T4b during surgery; (4) conversion to open surgery; (5) severe incapacitating disease (American Society of Anesthesiologists classification IV or V, ASA). A total of 666 patients with middle to low rectal cancer undergoing laparoscopic LAR in The First Affiliated Hospital of Army Medical University from January 2017 to June 2020 were enrolled. There were 473 males and 193 females with the median age of 59 (18-80) years. Laparoscopic LAR with peritoneum reconstruction was performed in 188 cases (PR group), and laparoscopic LAR without peritoneum reconstruction was performed in 478 cases (NPR group). After 1:1 propensity score matching according to 1:1 based on age, gender, body mass index, TNM staging, ASA classification, intraoperative blood loss, distance from tumor low margin to anal edge, 153 cases were included in each group. Postoperative complications were classified according to Clavien-Dindo classification. Anastomotic leakage was defined and graded according to the International Study Group of Rectal Cancer (ISGRC) criteria. Results: After propensity score matching, there were no significant differences in baseline demographic characteristics between the 2 groups (all P>0.05), indicating that these two groups were comparable. (1) Operative conditions: All the patients in both groups completed operation successfully. Compared with the NPR group, the PR group had longer operation time [(181.3±60.3) minutes vs. (168.9±51.5) minutes, t=2.185, P=0.029], shorter postoperative median hospital stay [8 (7, 10) days vs. 9 (7, 11) days, Z=-2.282, P=0.022], and the differences were statistically significant (P<0.05). (2) Postoperative complications: The overall morbidity of postoperative complication in PR group and NPR group was 20.3% (31/153) and 24.2% (37/153) respectively, and the incidence of anastomotic leakage was 9.8% (15/153) and 11.1%(17/153) respectively, whose differences were not statistically significant (both P>0.05). Compared with NPR group, PR group had lower morbidity of grade III to IV complications [3.9% (6/153) vs. 11.1% (17/153), χ(2)=5.688, P=0.017] and lower secondary operation rate [1.3% (2/153) vs. 5.9% (9/153), χ(2)=4.621, P=0.032], the differences were statistically significant (both P<0.05). Though PR group had lower incidence of grade C anastomoic leakage [1.3% (2/153) vs. 3.9% (6/153), χ(2)=2.054, P=0.152], but the differences were not statistically significant. (3) Postoperative inflammation: The difference of the procalcitonin level of both PR and NPR groups at postoperative 1-d, 3-d, and 5-d was statistically significant (F=5.222, P=0.010) in time-dependent manner, while the difference was not significant in the interaction effect (P>0.05). No statistically significant differences in the C-reactive protein level between two groups at postoperative 1-d, 3-d, and 5-d were found (all P>0.05). Conclusion: Peritoneum reconstruction in laparoscopic LAR can decrease the morbidity of postoperative complication of grade III to IV and the reoperation rate, and plays an important role in controlling the inflammatory reaction, which has great clinical value.

[Molecular characteristics of Legionella pneumophila in shower water of public places in Ma'anshan city from 2019 to 2020]

Objective: To understand the epidemiological and pathogenic characteristics of Legionella pneumophila in shower water of public places in Ma'anshan City from 2019 to 2020, and to provide scientific basis for further prevention and control of legionellosis. Methods: From 2019 to 2020, according to population density distribution and business scale of bathing places in the main urban area of Ma'anshan City (Huashan District and Yushan District), 8 public bathing places (including 3 large, 3 medium and 2 small) were selected to collect 308 shower water and water storage pool water samples (294 shower water samples and 14 water storage pool water samples). After the collected water samples were treated, cultured, isolated and identified, the type characteristics of Legionella pneumophila were analyzed. Results: Legionella pneumophila were detected in 120 water samples among 308 shower water and water storage pool water samples, with an overall positive rate of 39.0% (120/308). A total of 154 Legionella pneumophila strains were detected, including 10 different serotypes, predominated by serotype 1 (LP1) and serotype 3 (LP3), accounting for 40.9% (63/154) and 22.7% (35/154). Among 154 strains of Legionella pneumophila, 23 strains of Legionella pneumophila were positive for all 14 virulence genes, accounting for 14.9% (23/154), including 19 serotype 1 (LP1) and 4 serotype 8 (LP8). Pulsed field gel electrophoresis (PFGE) cluster analysis of 154 Legionella pneumophila strains showed 60 different patterns. Conclusion: Legionella pneumophila was seriously polluted in the shower water environment of public places in Ma^, anshan City. The serotypes are widely distributed and the virulence of the strains is strong. The results of molecular typing show that these strains have genetic diversity.

LASSO and Bioinformatics Analysis in the Identification of Key Genes for Prognostic Genes of Gynecologic Cancer

The aim of this study is to identify potential biomarkers for early diagnosis of gynecologic cancer in order to improve survival. Cervical cancer (CC) and endometrial cancer (EC) are the most common malignant tumors of gynecologic cancer among women in the world. As the underlying molecular mechanisms in both cervical and endometrial cancer remain unclear, a comprehensive and systematic bioinformatics analysis is required. In our study, gene expression profiles of GSE9750, GES7803, GES63514, GES17025, GES115810, and GES36389 downloaded from Gene Expression Omnibus (GEO) were utilized to analyze differential gene expression between cancer and normal tissues. A total of 78 differentially expressed genes (DEGs) common to CC and EC were identified to perform the functional enrichment analyses, including gene ontology and pathway analysis. KEGG pathway analysis of 78 DEGs indicated that three main types of pathway participate in the mechanism of gynecologic cancer such as drug metabolism, signal transduction, and tumorigenesis and development. Furthermore, 20 diagnostic signatures were confirmed using the least absolute shrink and selection operator (LASSO) regression with 10-fold cross validation. Finally, we used the GEPIA2 online tool to verify the expression of 20 genes selected by the LASSO regression model. Among them, the expression of PAMR1 and SLC24A3 in tumor tissues was downregulated significantly compared to the normal tissue, and found to be statistically significant in survival rates between the CC and EC of patients (p < 0.05). The two genes have their function: (1.) PAMR1 is a tumor suppressor gene, and many studies have proven that overexpression of the gene markedly suppresses cell growth, especially in breast cancer and polycystic ovary syndrome; (2.) SLC24A3 is a sodium–calcium regulator of cells, and high SLC24A3 levels are associated with poor prognosis. In our study, the gene signatures can be used to predict CC and EC prognosis, which could provide novel clinical evidence to serve as a potential biomarker for future diagnosis and treatment.

Abstract 2719: Interleukin-17 and cytokine-related signalings are determinants for tumor immune microenvironment in triple-negative breast cancer: in silico integrated analysis

Introduction: Programmed death (PD)-1/PD-ligand 1 immunotherapy increases the pathological complete response rate by 13.6 percentage points when added to neoadjuvant chemotherapy for early triple-negative breast cancer (TNBC) (Schmid et al. 2020). This indicates a proportion of TNBC are immune-responsive while many are not. We hypothesized that the tumor immune microenvironment might influence the clinical outcomes of TNBC patients. We wanted to investigate which signaling pathways could determine the TNBC being immune-hot or cold and have prognostication capability.

Methods: Dataset: TCGA-BRCA. Immune score (IS) and stromal score (SS) were calculated from the ESTIMATE and correlated with the documented overall survival. CIBERSORTx and Timer 2.0 were adopted for fractions of immune cell analysis. Differentially expressed genes (DEGs) were identified. Gene Ontology analysis and KEGG were adopted to study the enrichment of the gene sets. We explored and queried the cBioPortal for cancer genomics.

RESULTS: 115 patients with triple-negative breast cancer and 112 normal adjacent tissues were retrieved. The stromal score was high in 12 patients, and the immune score was high in another 12 patients. On Kaplan-Meier analyses, SS-low predicts higher overall survival (OS) vis-à-vis SS-high patients (P = 0.0081), while IS-high predicts higher OS as compared with IS-low patients (P = 0.2, too few cases in the IS-high). When compared with IS-low/SS-high patients, IS-high/SS-low patients had better OS (P = 0.045). In the tumor microenvironment (TME), a higher proportion of macrophages are in the M2 state in patients with IS-low/SS-high patients (P &lt; 0.001). More CD8+ cytotoxic T-cells in IS-high/SS-low patients (14.8% vs. 3.7%, p = 0.0286). More resting NK cells in IS-low/SS-high TME (P = 0.0108). DEGs analysis shows 651 DEGs (284 upregulated, 367 down) in IS-high/SS-low TME, whereas there were 370 DEGs (187 upregulated, 183 down) in IS-low/SS-high patients. The KEGG pathway analysis reveals the DEGs were enriched in the IL-17 signaling pathway and the cytokine-cytokine receptor interaction pathway. IL-17 is a proinflammatory cytokine that signals mainly via TRAF3 Interacting Protein 2 (TRAF3IP2), an inflammatory mediator and upstream regulator of several crucial transcription factors such as AP-1 and NF-κB. On the cBioPortal platform, we discovered that 13% of ER-negative, HER2-FISH-unamplified breast cancers harbor IL17RA deep deletion and 25% with TRAF3IP2 amplification.

Conclusions: The tumor microenvironment with each immune cell component determines the impact on women's survival with TNBC. IS-high/SS-low TME portends a better overall survival. We propose further studies to examine if an immune/stromal state also predicts the response to immunotherapy.

Citation Format: Victor C. Kok, Charles C. N. Wang, Szu-Han Liao, De-Lun Chen. Interleukin-17 and cytokine-related signalings are determinants for tumor immune microenvironment in triple-negative breast cancer: in silico integrated analysis [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 2719.

Abstract 2719: Interleukin-17 and cytokine-related signalings are determinants for tumor immune microenvironment in triple-negative breast cancer: in silico integrated analysis

Introduction: Programmed death (PD)-1/PD-ligand 1 immunotherapy increases the pathological complete response rate by 13.6 percentage points when added to neoadjuvant chemotherapy for early triple-negative breast cancer (TNBC) (Schmid et al. 2020). This indicates a proportion of TNBC are immune-responsive while many are not. We hypothesized that the tumor immune microenvironment might influence the clinical outcomes of TNBC patients. We wanted to investigate which signaling pathways could determine the TNBC being immune-hot or cold and have prognostication capability.

Methods: Dataset: TCGA-BRCA. Immune score (IS) and stromal score (SS) were calculated from the ESTIMATE and correlated with the documented overall survival. CIBERSORTx and Timer 2.0 were adopted for fractions of immune cell analysis. Differentially expressed genes (DEGs) were identified. Gene Ontology analysis and KEGG were adopted to study the enrichment of the gene sets. We explored and queried the cBioPortal for cancer genomics.

RESULTS: 115 patients with triple-negative breast cancer and 112 normal adjacent tissues were retrieved. The stromal score was high in 12 patients, and the immune score was high in another 12 patients. On Kaplan-Meier analyses, SS-low predicts higher overall survival (OS) vis-à-vis SS-high patients (P = 0.0081), while IS-high predicts higher OS as compared with IS-low patients (P = 0.2, too few cases in the IS-high). When compared with IS-low/SS-high patients, IS-high/SS-low patients had better OS (P = 0.045). In the tumor microenvironment (TME), a higher proportion of macrophages are in the M2 state in patients with IS-low/SS-high patients (P &lt; 0.001). More CD8+ cytotoxic T-cells in IS-high/SS-low patients (14.8% vs. 3.7%, p = 0.0286). More resting NK cells in IS-low/SS-high TME (P = 0.0108). DEGs analysis shows 651 DEGs (284 upregulated, 367 down) in IS-high/SS-low TME, whereas there were 370 DEGs (187 upregulated, 183 down) in IS-low/SS-high patients. The KEGG pathway analysis reveals the DEGs were enriched in the IL-17 signaling pathway and the cytokine-cytokine receptor interaction pathway. IL-17 is a proinflammatory cytokine that signals mainly via TRAF3 Interacting Protein 2 (TRAF3IP2), an inflammatory mediator and upstream regulator of several crucial transcription factors such as AP-1 and NF-κB. On the cBioPortal platform, we discovered that 13% of ER-negative, HER2-FISH-unamplified breast cancers harbor IL17RA deep deletion and 25% with TRAF3IP2 amplification.

Conclusions: The tumor microenvironment with each immune cell component determines the impact on women's survival with TNBC. IS-high/SS-low TME portends a better overall survival. We propose further studies to examine if an immune/stromal state also predicts the response to immunotherapy.

Citation Format: Victor C. Kok, Charles C. N. Wang, Szu-Han Liao, De-Lun Chen. Interleukin-17 and cytokine-related signalings are determinants for tumor immune microenvironment in triple-negative breast cancer: in silico integrated analysis [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 2719.

Abstract 2719: Interleukin-17 and cytokine-related signalings are determinants for tumor immune microenvironment in triple-negative breast cancer: in silico integrated analysis

Introduction: Programmed death (PD)-1/PD-ligand 1 immunotherapy increases the pathological complete response rate by 13.6 percentage points when added to neoadjuvant chemotherapy for early triple-negative breast cancer (TNBC) (Schmid et al. 2020). This indicates a proportion of TNBC are immune-responsive while many are not. We hypothesized that the tumor immune microenvironment might influence the clinical outcomes of TNBC patients. We wanted to investigate which signaling pathways could determine the TNBC being immune-hot or cold and have prognostication capability.

Methods: Dataset: TCGA-BRCA. Immune score (IS) and stromal score (SS) were calculated from the ESTIMATE and correlated with the documented overall survival. CIBERSORTx and Timer 2.0 were adopted for fractions of immune cell analysis. Differentially expressed genes (DEGs) were identified. Gene Ontology analysis and KEGG were adopted to study the enrichment of the gene sets. We explored and queried the cBioPortal for cancer genomics.

RESULTS: 115 patients with triple-negative breast cancer and 112 normal adjacent tissues were retrieved. The stromal score was high in 12 patients, and the immune score was high in another 12 patients. On Kaplan-Meier analyses, SS-low predicts higher overall survival (OS) vis-à-vis SS-high patients (P = 0.0081), while IS-high predicts higher OS as compared with IS-low patients (P = 0.2, too few cases in the IS-high). When compared with IS-low/SS-high patients, IS-high/SS-low patients had better OS (P = 0.045). In the tumor microenvironment (TME), a higher proportion of macrophages are in the M2 state in patients with IS-low/SS-high patients (P &lt; 0.001). More CD8+ cytotoxic T-cells in IS-high/SS-low patients (14.8% vs. 3.7%, p = 0.0286). More resting NK cells in IS-low/SS-high TME (P = 0.0108). DEGs analysis shows 651 DEGs (284 upregulated, 367 down) in IS-high/SS-low TME, whereas there were 370 DEGs (187 upregulated, 183 down) in IS-low/SS-high patients. The KEGG pathway analysis reveals the DEGs were enriched in the IL-17 signaling pathway and the cytokine-cytokine receptor interaction pathway. IL-17 is a proinflammatory cytokine that signals mainly via TRAF3 Interacting Protein 2 (TRAF3IP2), an inflammatory mediator and upstream regulator of several crucial transcription factors such as AP-1 and NF-κB. On the cBioPortal platform, we discovered that 13% of ER-negative, HER2-FISH-unamplified breast cancers harbor IL17RA deep deletion and 25% with TRAF3IP2 amplification.

Conclusions: The tumor microenvironment with each immune cell component determines the impact on women's survival with TNBC. IS-high/SS-low TME portends a better overall survival. We propose further studies to examine if an immune/stromal state also predicts the response to immunotherapy.

Citation Format: Victor C. Kok, Charles C. N. Wang, Szu-Han Liao, De-Lun Chen. Interleukin-17 and cytokine-related signalings are determinants for tumor immune microenvironment in triple-negative breast cancer: in silico integrated analysis [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 2719.

Kinking and cracking behavior in nacre under stepwise compressive loading

The damage evolution of nacre under compressive loading has not been well understood, despite numerous investigations on its compressive behavior. In the present work, quasi-in-situ loading-unloading-reloading stepwise compressive tests were performed on nacre in Pinctada maxima shell, which exhibits a distinctive gradient feature with the thickness of platelets decreasing from the external to internal parts. In the loading direction parallel to the platelets, multiple microcracks and kink bands can absorb much deformation energy, leading to a graceful failure. Kinking only occurs at the final stage of fracture process, and it thus has no obvious influence on the strength of nacre, but contributes to a much larger strain. In the loading direction perpendicular to the platelets, nacre exhibits concurrently much higher compressive strength and fracture strain, as the damage can be effectively restricted. This is attributed to the presence of gradient structure, which disperses the stress concentration in front of the crack tip, and arouses the toughening mechanisms including damage localization and crack deflection. The findings obtained in this study are expected to provide fundamental insights into the design of bio-inspired advanced engineering materials.

Deformation and fracture behavior of a natural shell ceramic: Coupled effects of shell shape and microstructure

Common seashells possess their most adaptive functions benefiting from the macro-geometry and unique microstructures. The Cymbiola nobilis shell exhibits a logarithmic spiral-like shape and it is hierarchically constructed by the fiber-like crossed-lamellar structure. Three-point bending tests are conducted on three groups of samples taken from different locations (G1 with two macro-layers, G2 with three macro-layers, and G3 containing three macro-layers but with an arch-like curved shape). A novel method was developed to evaluate the bending stress of the curved samples and understand the bending fracture resistance of such curved samples. Due to the presence of a horizontal force that can decrease or shield the bending moment at the bottom center of samples, the arch-like G3 samples demonstrate the highest bending fracture resistance, revealing the significance of the curved shape of shell in the protection against the external attacks. The number of macro-layers and the curved shape of shell play an important role in the mechanical properties of the shell. The orientation of building blocks in a single crossed-lamellar layer is critical to the fracture resistance, and five types of fracture modes based on interfacial debonding, inter- and trans-lamella fracture are identified. The results obtained in this study would help open a new pathway to the development of bio-inspired high-performance structural materials.

Thermodynamic and microstructural study of Ti2AlNb oxides at 800 °C

The high-temperature structural applications of Ti2AlNb-based alloys, such as in jet engines and gas turbines, inevitably require oxidation resistance. The objective of this study is to seek fundamental insight into the oxidation behavior of a Ti2AlNb-based alloy via detailed microstructural characterization of oxide scale and scale/substrate interface after oxidation at 800 °C using X-ray diffraction (XRD), scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and transmission electron microscopy (TEM). The oxide scale exhibits a complex multi-layered structure consisting of (Al,Nb)-rich mixed oxide layer (I)/mixed oxide layer (II)/oxygen-rich layer (III)/substrate from the outside to inside, where the substrate is mainly composed of B2 and O-Ti2AlNb phases. High-resolution TEM examinations along with high-angle annular dark-field (HAADF) imaging reveal: (1) the co-existence of two types (α and δ) of Al2O3 oxides in the outer scale, (2) the presence of metastable oxide products of TiO and Nb2O5, (3) an amorphous region near the scale/substrate interface including the formation of AlNb2, and (4) O-Ti2AlNb phase oxidized to form Nb2O5, TiO2 and Al2O3.

Mechanical properties of crossed-lamellar structures in biological shells: A review

The self-fabrication of materials in nature offers an alternate and powerful solution towards the grand challenge of designing advanced structural materials, where strength and toughness are always mutually exclusive. Crossed-lamellar structures are the most common microstructures in mollusks that are composed of aragonites and a small amount of organic materials. Such a distinctive composite structure has a fracture toughness being much higher than that of pure carbonate mineral. These structures exhibiting complex hierarchical microarchitectures that span several sub-level lamellae from microscale down to nanoscale, can be grouped into two types, i.e., platelet-like and fiber-like crossed-lamellar structures based on the shapes of basic building blocks. It has been demonstrated that these structures have a great potential to strengthen themselves during deformation. The observed underlying toughening mechanisms include microcracking, channel cracking, interlocking, uncracked-ligament bridging, aragonite fiber bridging, crack deflection and zig-zag, etc., which play vital roles in enhancing the fracture resistance of shells with the crossed-lamellar structures. The exploration and utilization of these important toughening mechanisms have attracted keen interests of materials scientists since they pave the way for the development of bio-inspired advanced composite materials for load-bearing structural applications. This article is aimed to review the characteristics of hierarchical structures and the mechanical properties of two kinds of crossed-lamellar structures, and further summarize the latest advances and biomimetic applications based on the unique crossed-lamellar structures.

Phenotypic Characterization of Insulin-Resistant and Insulin-Sensitive Obesity

CONTEXT

Whereas insulin resistance and obesity coexist, some obese individuals remain insulin sensitive.

OBJECTIVE

We examined phenotypic and metabolic factors associated with insulin sensitivity in both muscle and liver in obese individuals.

DESIGN AND PARTICIPANTS

Sixty-four nondiabetic obese adults (29 males) underwent hyperinsulinemic (15 and 80 mU/m(2) · min)-euglycemic clamps with deuterated glucose. Top tertile subjects for glucose infusion rate during the high-dose insulin clamp were assigned Musclesen and those in the lower two tertiles were assigned Muscleres. Secondarily, top tertile subjects for endogenous glucose production suppression during the low-dose insulin clamp were deemed Liversen and the remainder Liverres.

MAIN OUTCOMES MEASURES

Clinical and laboratory parameters and visceral, subcutaneous, liver, and pancreatic fat were compared.

RESULTS

Musclesen and Muscleres had similar body mass index and total fat (P > .16), but Musclesen had lower glycated hemoglobin (P < .001) and systolic (P = .01) and diastolic (P = .03) blood pressure (BP). Despite similar sc fat (P = 1), Musclesen had lower visceral (P < .001) and liver (P < .001) fat. Liversen had lower visceral (P < .01) and liver (P < .01) fat and C-reactive protein (P = .02) than Liverres. When subjects were grouped by both glucose infusion rate during the high-dose insulin clamp and endogenous glucose production suppression, insulin sensitivity at either muscle or liver conferred apparent protection from the adverse metabolic features that characterized subjects insulin resistant at both sites. High-density lipoprotein-cholesterol, 1-hour glucose, systolic BP, and triglycerides explained 54% of the variance in muscle insulin sensitivity.

CONCLUSIONS

Obese subjects who were insulin sensitive at muscle and/or liver exhibited favorable metabolic features, including lower BP, liver and visceral adiposity. This study identifies factors associated with, and possibly contributing to, insulin sensitivity in obesity.

Halo current diagnostic system of experimental advanced superconducting tokamak

The design, calibration, and installation of disruption halo current sensors for the Experimental Advanced Superconducting Tokamak are described in this article. All the sensors are Rogowski coils that surround conducting structures, and all the signals are analog integrated. Coils with two different cross-section sizes have been fabricated, and their mutual inductances are calibrated. Sensors have been installed to measure halo currents in several different parts of both the upper divertor (tungsten) and lower divertor (graphite) at several toroidal locations. Initial measurements from disruptions show that the halo current diagnostics are working well.

A Unified Model for the Prediction of Yield Strength in Particulate-Reinforced Metal Matrix Nanocomposites

Lightweighting in the transportation industry is today recognized as one of the most important strategies to improve fuel efficiency and reduce anthropogenic climate-changing, environment-damaging, and human death-causing emissions. However, the structural applications of lightweight alloys are often limited by some inherent deficiencies such as low stiffness, high wear rate and inferior strength. These properties could be effectively enhanced by the addition of stronger and stiffer reinforcements, especially nano-sized particles, into metal matrix to form composites. In most cases three common strengthening mechanisms (load-bearing effect, mismatch of coefficients of thermal expansion, and Orowan strengthening) have been considered to predict the yield strength of metal matrix nanocomposites (MMNCs). This study was aimed at developing a unified model by taking into account the matrix grain size and porosity (which is unavoidable in the materials processing such as casting and powder metallurgy) in the prediction of the yield strength of MMNCs. The Zener pinning effect of grain boundaries by the nano-sized particles has also been integrated. The model was validated using the experimental data of magnesium- and titanium-based nanocomposites containing different types of nano-sized particles (namely, Al₂O₃, Y₂O₃, and carbon nanotubes). The predicted results were observed to be in good agreement with the experimental data reported in the literature.

Successful ABO-incompatible living-related intestinal transplantation: a 2-year follow-up

ABO-incompatible intestinal transplantation has rarely been performed due to poor patient outcomes. Herein we present a case of successful ABO-incompatible intestinal transplantation with a 2-year follow-up. A 16-year-old female with a history of extensive bowel resection received an ABO-incompatible living donor bowel graft from her father (blood type AB graft into a type A recipient). Posttransplant immunosuppression consisted of an initial anti-CD20, plasmapheresis/intravenous immunoglobulin before transplantation, followed by an anti-thymocyte globulin (ATG) induction and splenectomy, and maintenance with tacrolimus and prednisone. Her postoperative course was remarkable for a single episode of rejection on day 14 which responded promptly to treatment with methyprednisolone and ATG. Three months after transplantation, the patient developed an abdominal abscess requiring open surgical drainage. No viral infections were encountered. Posttransplant anti-B antibody titers and anti-B7 donor-specific antibody levels remained low. At a 2-year follow-up, the patient showed a progressive weight gain of 5.0 kg. This case illustrates that ABO-incompatible living-related bowel transplantation is immunologically feasible and is associated with good outcomes for the recipient. The management of blood type antibodies and the use of adequate immunosuppression in the early period of the procedure may be the keys to the success of future cases.

Roles of pyrolysis on availability, species and distribution of Cu and Zn in the swine manure: chemical extractions and high-energy synchrotron analyses

Animal manures generally contain high levels of heavy metals that may pose a significant threat to soil and groundwater qualities. Pyrolysis as means of reducing metal availability in such feed stocks is recently encouraged, but systematic studies are currently lacking. The aim of this study was to assess the impact of pyrolysis temperature on the availability of Cu and Zn by chemical extraction, to determine the speciation of Cu and Zn by synchrotron-based X-ray spectroscopy, and finally to investigate the phase distribution of metal species in the carbonaceous materials by combining acid-base extractions and absorption spectroscopy data. The results showed that both Cu and Zn in the swine manure were mainly bound to organic functional groups. Cu (II) reduction and Cu (I)-S complexes were observed during the pyrolysis process. Zn species resembling ZnAc2 was still dominant, being 60.8-69.2%, and ZnS increased by 6.6-21.8% in the carbonaceous materials. The distribution of Cu and Zn in the mineral, carbonized and non-carbonized organic phases varied greatly with the pyrolysis temperature. The higher the temperature, the more the metals existed in the mineral phase and carbonized organic phase. The decrease of EDTA extractable Cu and Zn with pyrolysis temperature was due to the increase of metals in the carbonized organic phase and mineral phase. It is suggested that pyrolysis at the relatively higher temperature is a better choice for metal-containing manure according to the metal speciation, solubility and availability.

Five new norditerpenoid alkaloids from Aconitum sinomontanum

From the roots of Aconitum sinomontanum, five new norditerpenoid alkaloids, sinomontanitines A (1) and B (2), sinomontanines A (3), B (4) and C (5), were isolated together with the known alkaloids lappaconitine (6) and ranaconitine (7), The structures of the new alkaloids were determined by spectral analysis.

Aux/IAA proteins are phosphorylated by phytochrome in vitro

Auxin/indole-3-acetic acid (Aux/IAA) genes encode short-lived transcription factors that are induced as a primary response to the plant growth hormone IAA or auxin. Gain-of-function mutations in Arabidopsis genes, SHY2/IAA3, AXR3/IAA17, and AXR2/IAA7 cause pleiotropic phenotypes consistent with enhanced auxin responses, possibly by increasing Aux/IAA protein stability. Semidominant mutations shy2-1D, shy2-2, axr3-1, and axr2-1 induce ectopic light responses in dark-grown seedlings. Because genetic studies suggest that the shy2-1D and shy2-2 mutations bypass phytochrome requirement for certain aspects of photomorphogenesis, we tested whether SHY2/IAA3 and related Aux/IAA proteins interact directly with phytochrome and whether they are substrates for its protein kinase activity. Here we show that recombinant Aux/IAA proteins from Arabidopsis and pea (Pisum sativum) interact in vitro with recombinant phytochrome A from oat (Avena sativa). We further show that recombinant SHY2/IAA3, AXR3/IAA17, IAA1, IAA9, and Ps-IAA4 are phosphorylated by recombinant oat phytochrome A in vitro. Deletion analysis of Ps-IAA4 indicates that phytochrome A phosphorylation occurs on the N-terminal half of the protein. Metabolic labeling and immunoprecipitation studies with affinity-purified antibodies to IAA3 demonstrate increased in vivo steady-state levels of mutant IAA3 in shy2-2 plants and phosphorylation of the SHY2-2 protein in vivo. Phytochrome-dependent phosphorylation of Aux/IAA proteins is proposed to provide one molecular mechanism for integrating auxin and light signaling in plant development.

Use of pK(a) differences to enhance the formation of base triplets involving C-G and G-C base pairs

Two C-nucleosides are employed for the recognition of dC-dG base pairs. Both derivatives are related to dC but lack the O2-carbonyl. The absence of the carbonyl should eliminate any unfavorable steric interactions at this site. One of the derivatives contains a 2-aminopyridine heterocycle (d2APy) while the second contains a 2-aminopyrimidine heterocycle (d2APm). The former with a pK(a) of 6. 8 functions better for the recognition of dG-dC base pairs than it does in the binding to dC-dG base pairs. The d2APm derivative with a pK(a) of 3.3 functions better to form base triplets with dC-dG base pairs than with dG-dC targets. Triplex T(m)'s in both cases are compared with the sequence containing the native dC residue. The dC analogues appear to make two hydrogen bonds to a target dG base residue, one of which requires protonation of the ring nitrogen. Recognition of a target dC residue appears to require the formation of a single hydrogen bond to the C-nucleoside and having that nitrogen largely in the unprotonated state facilitates its formation.

Conditional identification of phosphate-starvation-response mutants in Arabidopsis thaliana

Plants have evolved elaborate metabolic and developmental adaptations to low phosphorus availability. Biochemical responses to phosphate limitation include increased production and secretion of phosphate-acquisition proteins such as nucleases, acid phosphatases, and high-affinity phosphate transporters. However, the signal transduction pathways that sense phosphate availability and integrate the phosphate-starvation response in plants are unknown. We have devised a screen for conditional mutants in Arabidopsis thaliana (L.) Heynh. to dissect signaling of phosphate limitation. Our genetic screen is based on the facultative ability of wild-type Arabidopsis plants to metabolize exogenous DNA when inorganic phosphate is limiting. After screening 50,000 M2 seedlings, we isolated 22 confirmed mutant lines that showed severely impaired growth on medium containing DNA as the only source of phosphorus, but which recovered on medium containing soluble inorganic phosphate. Characterization of nine such mutant lines demonstrated an inability to utilize either DNA or RNA. One mutant line, psr1 (phosphate starvation response), had significantly reduced activities of phosphate-starvation-inducible isoforms of ribonuclease and acid phosphatase under phosphate-limiting conditions. The data suggest that a subset of the selected mutations impairs the expression of more than one phosphate-starvation-inducible enzyme required for utilization of exogenous nucleic acids, and may thus affect regulatory components of a Pi starvation response pathway in higher plants.

Nucleoside analogue substitutions in the trinucleotide DNA template recognition sequence 3'-(CTG)-5' and their effects on the activity of bacteriophage T7 primase

Bacteriophage T7 primase catalyzes the synthesis of the oligoribonucleotides pppACC(C/A) and pppACAC from the single-stranded DNA template sites 3'-d[CTGG(G/T)]-5' and 3'-(CTGTG)-5', respectively. The 3'-terminal deoxycytidine residue is conserved but noncoding. A series of nucleoside analogues have been prepared and incorporated into the conserved 3'-d(CTG)-5' site, and the effects of these analogue templates on T7 primase activity have been examined. The nucleosides employed include a novel pyrimidine derivative, 2-amino-5-(beta-2-deoxy-D-erythro-pentofuranosyl)pyridine (d2APy), whose synthesis is described. Template sites containing d2APy in place of the cryptic dC support oligoribonucleotide synthesis whereas those containing 3-deaza-2'-deoxycytidine (dc(3)C) and 5-methyl-6-oxo-2'-deoxycytidine (dm(5ox)C) substitutions do not, suggesting that the N3 nitrogen of cytidine is used for a critical interaction by the enzyme. Recognition sites containing 4-amino-1-(beta-2-deoxy-D-erythro-pentofuranosyl)-5-methyl-2,6[1H, 3H]-pyrimidione (dm(3)2P) or 2'-deoxyuridine (dU) substitutions for dT support oligoribonucleotide synthesis whereas those containing 5-methyl-4-pyrimidinone 2'-deoxyriboside (d(2H)T) substitutions do not, suggesting the importance of Watson-Crick interactions at this template residue. Template sites containing 7-deaza-2'-deoxyguanosine (dc(7)G) or 2'-deoxyinosine (dI) in place of dG support oligoribonucleotide synthesis. The reduced extent to which dc(7)G is successful within the template suggests a primase-DNA interaction. Inhibition studies suggest that the primase enzyme binds "null" substrates but cannot initiate RNA synthesis.

Detection of specific antibodies to an antigenic mannoprotein for diagnosis of Penicillium marneffei penicilliosis

The disseminated and progressive fungal disease Penicillium marneffei penicilliosis is one of the most common infectious diseases in AIDS patients in Southeast Asia. To diagnose systemic penicilliosis, we developed an enzyme-linked immunosorbent assay (ELISA)-based antibody test with Mp1p, a purified recombinant antigenic mannoprotein of P. marneffei. Evaluation of the test with guinea pig sera against P. marneffei and other pathogenic fungi indicated that this assay was specific for P. marneffei. Clinical evaluation revealed that high levels of specific antibody were detected in two immunocompetent penicilliosis patients. Furthermore, approximately 80% (14 of 17) of the documented penicilliosis patients with human immunodeficiency virus tested positive for the specific antibody. No false-positive results were found for serum samples from 90 healthy blood donors, 20 patients with typhoid fever, and 55 patients with tuberculosis, indicating a high specificity of the test. Thus, this ELISA-based test for the detection of anti-Mp1p antibody can be of significant value as a diagnostic for penicilliosis.

G-band expression and megabase fragmentations in apoptosis

Apoptosis seems characterized by a cascade of megabase to 200-bp fragmentations and by a commitment to perish at the initial level. How that could be achieved seems unclear. Preferential cleavage of transcriptionally active chromatin by apoptotic nuclease activity has long been suggested. We show here the manifestation of self-inflicted G-banding patterns in mitotic chromosomes, or G-band expression, occurring concurrently with a pattern of megabase fragmentations in two apoptotic systems that we have established in human Chang liver cells using (a) staurosporine and (b) vanadyl(4) prepulsing. We further show that rare-cutting NotI and MluI restriction endonucleases with C-G dinucleotide sequence specificity had produced similar G-bandings and megabase fragmentations cascading down to the 200-bp ladder fragmentation that were also associated with the expression of characteristic apoptotic morphologies by the digested cells. CpG-specific methylation using the methylase SssI abolished the DNA fragmentation cascade, G-banding, and apoptotic expressions induced by NotI and MluI, implicating endonuclease cleavage of active chromatin, where CpG islands are concentrated, as the initiating event. Reproducing the G-bandings and megabase fragmentations by directly applying NotI and MluI endonucleases to fixed chromosomes and extracted genomic DNA, respectively, further confirmed the notion of endonucleolytic cleavage of active chromatin as the causation. Nuclease-digested light G-band regions of chromosomes appeared to be the chromosome sites providing the megabase fragments. Transcriptionally active genes of the genome are known to be preferentially cleaved by nuclease activity and are established as being concentrated in the light G-bandings that correspond to R-bandings, which are also known to be the sites of more frequent cytogenetic breakpoints. Manifestation of self-inflicted G-banding patterns (G-banding expression) in apoptosis would then imply cleavage of the transcriptionally active genes in every light G-band site of every chromosome in the genome. This must be suicidal.

Pain responses in patients with upper-extremity disorders

The purpose of this study was to evaluate the relationship between pain response factors and upper-extremity disorders associated with work-related compensable disorders. In this retrospective study, the charts of 113 patients were examined. Compensation was not found to have any statistically significant association with pain levels. The degree of functional overlay in these patients, indicated by pain questionnaire scores, differed only slightly between compensated and noncompensated patients and indicated no significant difference between the 2 groups, except that the compensated group used a higher number of descriptors to describe their pain (p = .0143). These results indicate that compensation affects the verbalization of pain but does not affect the degree of pain experienced. Working status was found to be significantly correlated with a better ability to cope with stress at home, suggesting that employment status may be a more important factor than compensation status in the presentation of these patients.

Transient G2M arrest and subsequent release of apoptotic and mitotic cells in vanadyl(4)-prepulsed human Chang liver cells

The relationship between cell cycling and apoptosis/programmed cell death has been perceived as either checkpoint arrests or mitotic aberration where common pathways between mitosis and apoptosis seem suggested. We show here evidence implicating both perceptions of cell cycle involvement. The process was initiated by hydroxyl free radicals (OH*) generated intracellularly from internalized vanadyl(4). Intranuclear sequestration of vanadyl(4) was verified by nuclear microscopy. Resultant high oxidative reactivity in the nucleus was shown by the redox indicator methylene blue, suggesting direct oxidative damage to genomic DNA. Oxidative stress was further enhanced by depletion of glutathione which is the main cellular reducing agent. Genomic degradation and fragmentation was confirmed by flow cytometric evaluation of terminal deoxynucleotidyl transferase (TdT)-mediated 3'OH end-labelling (TUNEL) of DNA nicks, and cell cycle DNA profiling demonstrating sub-G1 (sub-2N) accumulation. With DNA degradation, there was a G2M transient with hyperdiploid right-shifting, consistent with G2 arrest. G2 arrest was subsequently 'released' with abolition of G2M and all other cell cycle phases except for a solitary sub-G1 (apoptotic) peak. The cytological profile of this 'release' phenomenon was initially marked by the appearance of clusters of mitotic and apoptotic cells. At later stages, the cell population was composed exclusively of nuclear ghosts, apoptotic cells, mitotic cells, and mitotic cells with both chromosomes and apoptotic condensations. Concurrent and conjoint expression of cell death and cell division as the exclusive process of an entire cell population refuted the notion of mutual exclusivity between life and death. Zn2+, an endonuclease inhibitor, abolished all observed cytological and DNA profile changes.

A case-control study of risk factors of nasopharyngeal carcinoma

Risk factors and nasopharyngeal carcinoma (NPC) in residents of Guangzhou city were investigated in a case-control study: 104 cases were compared with an equal number of age, sex, and neighborhood-matched controls. The results of multiple conditional regression of logistic model showed that plum vegetable (adjusted OR = 1.81, 95% CI 1.01-3.33), preserved prune (adjusted OR = 2.95, 95% CI 1.04-8.41), no separate kitchen (if >35 years, adjusted OR = 1.98, 95% CI 1.24-3.75), kitchen range without chimney (if >10 years, adjusted OR = 2.72, 95% CI 1.56-4.73) and hereditary factor (adjusted OR = 8.27, 95% CI 1.94-35.54) were significantly associated with an increased risk of NPC. Grape (adjusted OR = 0.31, 95% CI 0.17-0.58) may be a protective factor.

Effects of retinoid X receptor-selective ligands on proliferation of prostate cancer cells

BACKGROUND

Management of prostate cancer that either is detectable by prostate specific antigen (PSA) measurements after curative intent or has spread outside of its capsule is a serious problem. Innovative, nontoxic approaches to the disease are required. One approach might be therapy with retinoids. Retinoid activities are mediated by two distinct families of transcription factors: the retinoic acid receptors (RARs) and retinoid X receptors (RXRs), which can induce transcriptional activation through specific DNA sites or by inhibiting the transcription factor AP-1 that usually mediates cellular proliferative signals. The RARs require heterodimerization with RXRs. RXRs can form either heterodimers or homodimers; and the latter can bind to DNA response elements that are distinct from those bound by the RAR/RXR heterodimers.

METHODS

A series of novel synthetic retinoids that selectively interact with RXR/RXR homodimers or RAR/RXR heterodimers, or that selectively inhibit AP-1 activity without activating transcription were evaluated for their ability to inhibit clonal growth of three human prostate cancer cell lines (PC-3, DU-145, and LNCaP).

RESULTS

Several notable findings were: 1) RXR-selective retinoids, such as SR11246, were able to inhibit the clonal growth of prostate cancer cells. In contrast, SR11246 had little effect on clonal growth of myeloid leukemic cells. 2) RAR-selective retinoids also inhibited clonal growth of prostate cancer cells. 3) The retinoid (SR11238) with potent anti-AP-1 activity had no effect on the clonal growth of prostate cancer cells.

CONCLUSIONS

This study shows that both RXR- and RAR-selective retinoids are worthy of further study and may be candidates for future clinical trials in prostate cancer.

Effects of potent vitamin D3 analogs on clonal proliferation of human prostate cancer cell lines

BACKGROUND

Management of prostate cancer that has spread outside of the prostate capsule is a difficult problem. Innovative, non-toxic approaches to the disease are required. New, relatively non-toxic vitamin D3 analogs have recently been synthesized. We report that several of these compounds have marked antiproliferative effects on prostate cells.

METHODS

The clonal antiproliferative activity of five novel analogs of 1,25 dihydroxyvitamin D3 [1,25(OH)2D3, (cmpd C)] as well as 1,25(OH)2D3 itself was tested on three human prostate cancer cell lines (PC-3, LNCaP, and DU-145). The analogs were 20-epi-22oxa-24a,26a,27a-tri-homo-1 alpha,25(OH)2D3 (code name: KH 1060); 24a26a27a-tri-homo-22,24-diene-1 alpha,25(OH)2D3 (code name: EB 1089); 1,25(OH)2-16ene-D3 (code name: HM); 1,25(OH)2-16ene-23yne-D3 (code name: V); 1,25(OH)2-20-epi-D3 (code name: MC 1288)].

RESULTS

With the parent compound [1,25(OH)2D3], the effective dose that inhibited 50% clonogenic growth of PC-3 and LNCaP was 10(-8)M and 7 x 10(-9)M, respectively. For these prostate cancer cell lines, KH 1060 was the most potent analog by an order of 25- to 35-fold as compared to cmpd C. The second and third most potent analogs were HM and MC 1288. DU-145 was resistant to all the vitamin D3 analogs. The major side-effect of 1,25(OH)2D3 is the production of hypercalcemia. The relative inhibitory index (RII) was determined by comparing the antiproliferative activity of the analog to its ability to produce hypercalcemia in mice injected intraperitoneally every other day. The KH 1060 had the best RTI: 50- to 70-fold greater than 1,25(OH)2D3 for PC-3 and LNCaP, respectively.

CONCLUSIONS

A trial of one or more of these innovative compounds should be considered for treatment of minimal residual disease of prostate cancer.

Effects of novel retinoid X receptor-selective ligands on myeloid leukemia differentiation and proliferation in vitro

The biologic effects of retinoids such as all-trans-retinoic acid (ATRA) and 9-cis-retinoic acid on proliferation and differentiation of hematopoietic cells are mediated by binding and activating two distinct families of transcription factors: the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs). The RARs require heterodimerization with RXRs; in addition, RXRs can form homodimers, which can bind to DNA response elements that are either distinct or the same as those bound by the RAR/RXR heterodimers. Therefore, the two retinoid pathways provide sequences that are specific for effective DNA binding and activation of target genes. We have developed several series of novel synthetic retinoids that selectively interact with RXR/RXR homodimers and RAR/RXR heterodimers. We show here that SR11236 and SR11246, which are RXR-selective analogs, had little ability to inhibit clonal growth and induce differentiation of leukemic cells (HL-60 cells and fresh acute myeloid leukemia cells). However, SR11249, SR11256, and LGD1069, which activated both RXR/RXR homodimers and RAR/RXR heterodimers, could inhibit clonal growth and induce differentiation of HL-60 cells as well as leukemic cells from patients, including those with acute promyelocytic leukemia (APL). This is similar to results observed with RAR/RXR-specific ligands. Interestingly, the combination of ATRA and either SR11249, SR11256, or LGD1069 showed synergistic effects in inducing differentiation of HL-60 cells. A retinoid (SR11238) with strong anti-AP-1 activity that did not activate the RARs and RXRs for gene transcription from the response element TREpal was inactive in our assay systems, suggesting that the antiproliferative effects of retinoids on leukemic cells is not mediated by inhibiting the AP-1 pathway. We conclude that the RAR/RXR pathway is more important than RXR/RXR pathway for differentiation and proliferation of acute myeloid leukemic cells, and certain retinoids or combination of retinoids with both RAR and RXR specificities may synergistically enhance the differentiation activity of ATRA, which may be relevant in several clinical situations.

Study of 45 cases of nasopharyngeal carcinoma with dermatomyositis

The authors have conducted a study of 61 cases of nasopharyngeal carcinoma (NPC) with dermatomyositis (DM) admitted to the hospital between April 1964 and May 1989 and accounting for 0.027% (61/226, 183) of all the malignant tumors at the hospital and 0.086% (61/70,899) of the nasopharyngeal carcinoma cases, during that time period. We have analyzed 45 cases with complete data, using equal number of age-, sex-, and stage-matched cases with only NPC as control. The findings show a 5- and 10-year survival rate and distant metastatic rate of 50.4, 34.5, and 40.5% respectively, for NPC with DM, and 57.8, 55.2, and 56.5% for controls. The results indicated that the radiotherapy with prednisone treatment not only is quite effective but also will not result in a significantly increased rate of distant metastasis.

Estimation of nitrification rates in flooded soils

Three techniques for estimating nitrification rates in flooded soils were evaluated in short-term incubation experiments using three soils. The techniques were based on inhibition of either ammonium or nitrite oxidation and (13)N isotope dilution. Of four inhibitors of ammonium oxidation evaluated, one (allylthiourea) was ineffective and two (2-ethynylpyridine or phenyl acetylene dissolved in ethanol) promoted immobilization of ammonium. Emulsified 2-ethynylpyridine and acetylene were equally effective inhibitors of ammonium oxidation and had little or no effect on gross rates of N mineralization and immobilization. Four inhibitors of nitrite oxidation were evaluated, but this approach was compromised by the nonspecificity of three of the compounds-potassium cyanide, 2-ethylamino-4-isopropylamino-6-methylthio-s-triazine (ametryne) and 3-(3,4-dichlorophenyl)-1-methylurea (DMU)-and by the partial effectiveness of another (potassium chlorate). Two methods based on isotope dilution gave similar estimates of nitrification rates. These rates were similar to those estimated by inhibition of ammonium oxidation in one soil but were lower in the other two soils. In the latter two soils, nitrification of labeled ammonium derived from dissimilatory nitrate reduction resulted in underestimation of nitrification rates by isotope dilution.

Antibacterial activity of cefprozil in vitro

Cefprozil is a new orally active cephalosporin which is undergoing in vitro and in vivo evaluations. Using the standard agar dilution method we compared the in vitro activity of this drug with other oral cephalosporins and ciprofloxacin against 637 recent clinical isolates from the Kaohsiung Veterans General Hospital, Taiwan. Against Escherichia coli and Klebsiella pneumoniae, cefprozil showed good activity, inhibiting over 80% of these isolates at 8 mg/l. Like other oral drugs of its class, it had little activity against Pseudomonas aeruginosa and Acinetobacter spp. Against Haemophilus influenzae, irrespective of beta-lactamase production, its activity was similar to comparable drugs. Against methicillin-susceptible Staphylococcus aureus, cefprozil showed high activity, inhibiting 90% of these isolates at 4 mg/l, whereas against methicillin-resistant S. aureus, its activity was higher than that of other oral cephalosporins tested and was similar to that of ciprofloxacin. Of enterococci tested, 57.7% were inhibited by 8 mg/l of cefprozil. Against beta-hemolytic streptococci, its activity was superior to all other drugs tested. The results of this in vitro study indicate that oral administration of cefprozil might be efficacious in the treatment of community-acquired cutaneous, respiratory and urinary tract infections.

Absence of WAF1 mutations in a variety of human malignancies

A newly cloned gene named wild-type p53-activated fragment 1 (WAF1; also known as p21, Pic-1, Cip-1, or SDI1) is directly regulated by p53 and can itself suppress tumor cell growth in culture. Induction of expression of WAF1 may be an important means by which cells with DNA injury arrest their growth to repair DNA or undergo apoptosis. Based on the hypothesis that mutations of this gene may play a role in carcinogenesis, we have studied 351 DNAs from 14 kinds of malignancies, as well as 36 human transformed cell lines, for alterations of WAF1 gene by single-strand conformation polymorphism analysis of polymerase chain reaction amplification of the DNA coding region of the WAF1 gene. No abnormal band shifts of WAF1 were noted in any of the samples or cell lines, but three major variants in exons 2 and 3 of the gene were found that are consistent with the existence of two different DNA polymorphisms. Sequence analysis of the amplified products producing these three variants in each exon from normal DNAs confirmed the presence of the polymorphisms in the WAF1 gene. Of 290 selected tumor samples previously evaluated for p53 mutations by single-strand conformation polymorphism, 90% had no detectable p53 alterations. In summary, mutations within the coding portion of the WAF1 gene were undetectable in a large series of human tumors, many of which had a normal p53 gene. This suggests that WAF1 alterations are generally caused indirectly, through p53 mutations rather than through intragenic mutation of the WAF1 itself.

Agonist and antagonist specificities of decidual prostaglandin-releasing oxytocin receptors and myometrial uterotonic oxytocin receptors in pregnant rats

This paper describes further pharmacological characterization of the decidual prostaglandin-releasing oxytocin receptors and the myometrial uterotonic oxytocin receptors in the uterus of the pregnant rat. The effects of oxytocin, arginine-vasopressin and their related agonists and antagonists on the release of PGF2 alpha were studied in vitro on isolated uteri from rats on day 19-20 of pregnancy that had been incubated in Krebs buffer, pH 7.4, at 37 degrees C. The concentration of PGF2 alpha in the media was measured using specific radioimmunoassays. It was found that the decidual and myometrial oxytocin receptors exhibit different ligand specificities. Of the agonists tested, oxytocin and arginine-vasopressin stimulated PGF2 alpha release in a dose-dependent manner. Arginine-vasopressin has only 3% of the uterotonic potency of oxytocin, but was found to have 16% of its PGF2 alpha-releasing activity. [4-Threonine, 7-glycine]oxytocin, a highly potent and selective uterotonic oxytocin analogue, had no detectable prostaglandin-releasing activity at a dosage 30 times higher than oxytocin. However, 1-deamino-[8-D-arginine]vasopressin, a highly potent and selective antidiuretic arginine-vasopressin analogue, which has only 10% of the uterotonic activity of arginine-vasopressin, was as potent as arginine-vasopressin in prostaglandin-releasing activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Myeloid differentiation mediated through retinoic acid receptor/retinoic X receptor (RXR) not RXR/RXR pathway

Retinoids, such as all-trans-retinoic acid and 9-cis-retinoic acid, are naturally occurring ligands of the nuclear retinoic acid receptors (RARs). In concert with binding of ligand, these receptors from heterodimers with the retinoic X receptor (RXR) and transactivate RAR/RXR-responsive genes. Retinoids can differentiate leukemic cell lines in vitro and induce clinically complete remissions in patients with acute promyelocytic leukemia. Synthetic ligands to the RAR and RXR receptors have been developed that selectively bind and activate RAR/RXR (TTAB) and RXR/RXR dimers (SR11217). We investigated the affect of these ligands, either alone or in combination, on in vitro growth and differentiation of cells from the HL-60, KG-1, THP-1, and WEHI-3 myeloid cell lines as well as on clonal growth of fresh myeloid leukemic blasts from patients. Clonal inhibition of proliferation of these cells was studied in soft agar cultures. Cells were plated in the presence of either one or a combination of retinoids at concentrations of 10(-5) to 10(-10) mol/L. TTAB inhibited 50% clonal growth at an effective dose (ED50) that was about 1,000-fold lower than the concentration of SR11217 required to achieve an ED50 for the same leukemic cells. Combination of both ligands at a variety of concentrations showed no synergistic effects. Superoxide production (nitroblue tetrazolium reduction) and CD11b expression as parameters of differentiation of HL-60 cells were also examined. Results paralleled those of clonal growth, with SR11217 being markedly less potent than TTAB. These results show that the ligand selective for RXR-homodimers has little effect on either inducing differentiation or inhibiting clonal growth of leukemic cells. The differentiating and antiproliferative effects of retinoids are mainly induced through RAR/RXR heterodimers, and development of therapeutic analogs should focus on this category of retinoids.

Transactivational and DNA binding abilities of endogenous p53 in p53 mutant cell lines

Cells with divergent mutant alleles of the p53 gene have different biological and biochemical properties in vitro. Increasing evidence indicates that p53 is a transcriptional activator, and recently, high affinity DNA binding sites for p53 have been identified. The purpose of this study was to determine in vivo, the effect that various mutant p53 proteins have on their ability to mediate transactivation and to bind specifically to DNA. Either a p53 responsive or control reporter gene was transfected into 18 human carcinoma cell lines, having various p53 mutations, either with or without a wild-type p53 expression vector. The CAT activity and DNA gel retardation were studied to measure transactivation and DNA binding by these endogenous p53s. As expected, the endogenously produced wild-type p53 binds to DNA binding sequences and can transactivate a reporter construct containing a p53 high affinity DNA binding site. Four of five cell lines with homozygous p53 mutations at codon 273 (273His), contained p53 which had the ability to bind to p53 DNA binding sequences and transactivate. In contrast, all the homozygous, non-codon 273 mutant p53s (156Pro, 175His, 223Leu, 248Gln, 248Trp, 280Lys) present in the other cell lines had no transactivating ability. These findings suggest that the biology of cancers with mutations at codon 273 may be different than those with p53 mutations at other sites. The p53 from WRO, a thyroid carcinoma cell line with p53 mutation at codon 223 (223Leu), was able to bind p53 DNA recognition sequences, but was unable to transactivate. Interestingly, in a vulvar carcinoma cell line (A431) with a p53 mutation at codon 273 (273His), the p53 was unable to transactivate and gave an aberrant band on gel retardation. Both CEM and SK-UT-1, which have compound heterozygous mutations at codons 175/248 (175His/248His), produced p53 which can complex with DNA, as well as transactivate. In contrast, the p53 in cell lines with either homozygous 175His or 248His p53 mutations, were unable either to transactivate or bind to the p53 response element. A cell line (NPA) heterozygous for 266Glu p53 mutation, was able to efficiently transactivate a reporter containing a p53 DNA binding site, therefore showing no evidence of a dominant negative effect of the endogenous p53 mutant allele. In summary, this in vivo study further supports the idea that different p53 mutant alleles have various properties which may affect their function.

Reducing denitrification loss with nitrification inhibitors following presowing applications of urea to a cottonfield

The effects of the nitrification inhibitors nitrapyrin, acetylene (provided by wax-coated calcium carbide), and phenylacetylene on nitrogen (N) transformations and denitrification losses following presowing applications of urea were determined in a cottonfield in the Namoi Valley of New South Wales. The study used 0.05-m-diameter microplots to follow the changes in mineral N, and 0.15-m-diameter microplots fertilised with 15N-labelled urea (6 g N/ m2; 5 atom % 15N) to assess losses of applied N. When urea was applied in February (34 weeks before sowing), 84% of applied N was lost from the soil. Loss of applied N was reduced by addition of nitrapyrin and phenylacetylene, to 53 and 57%, respectively. In the absence of nitrification inhibitors, less N was lost (72% of that applied) from an application in May than from the February application. Addition of acetylene, phenylacetylene, and nitrapyrin reduced losses over the 24 weeks to sowing to 57, 52, and 48%, respectively. These experiments show that N loss from presowing applications of urea can be significantly reduced by the use of nitrification inhibitors, but that the losses of N are still substantial.

Analysis of p53 mutations in a large series of lymphoid hematologic malignancies of childhood

p53 mutations are found in a wide variety of cancers, including hematologic malignancies. These alterations apparently contribute to development of the malignant phenotype. We analyzed a large series of lymphoid (330 cases) and a smaller series of myeloid (29 cases) malignancies of childhood for p53 mutations by single-strand conformational polymorphism (SSCP) following polymerase chain reaction. Samples with abnormal SSCP were reamplified and analyzed by direct sequencing method. p53 mutations were detected within the known mutational hotspots (exons 5 to 8) in 8 of 330 lymphoid malignancies, and in none of 29 myeloid malignancies, showing that the frequency of p53 mutations in childhood lymphoid malignancies was very low (8 of 330 cases [2%]). Four of these patients had very aggressive, fatal acute lymphocytic leukemia (ALL). None of 13 infants and none of 48 patients with T-lineage leukemia had detectable p53 mutations in their ALL cells. Exceptionally, p53 mutations were comparatively frequent in a small sample of B-cell non-Hodgkin's lymphomas (2 of 8 cases). Mutations were detected in samples from two patients with ALL at relapse; these were not detected in samples at initial diagnosis from the same patients, suggesting that p53 mutations may be associated with progression to a more malignant phenotype. Seven of eight alterations of p53 were missense mutations, and seven of eight samples may be heterozygous for the mutant p53, indicating that p53 protein may act in a dominant negative fashion.

Analysis of p53 transactivation through high-affinity binding sites

Alterations or elimination of the p53 protein is frequently occurring during human carcinogenesis. Overexpression of wild-type p53 has a profound growth-inhibitory effect on many cell lines, including strong and apparently non-sequence specific repression of a number of promoters. Consistent with the hypothesis that it acts as transcriptional regulator, wild-type p53 protein binds DNA and activates transcription of several promoters. We have studied DNA binding and transactivation (TA) properties of human wild-type and mutant p53 proteins representing four major mutational hotspots. DNA-gel retardation was used to detect specific p53-DNA complexes in nuclear extracts, with radiolabelled oligonucleotides representing high affinity p53-binding sites (HBS) as a probe. p53-specific complexes were identified by competition with unlabelled 'self' oligos and by double band-shifts in the presence of anti-p53 antibodies. To show transactivation by p53, TK promoter-driven CAT reporter gene was placed 3' of the p53-binding site. CAT activity was assayed after co-transfection of reporters with either wild-type (WT) or mutant p53 expression constructs into human cells that do not express p53 (SKOV3). We found that wild-type p53 has strong transactivating effect on the reporter. All mutants, with the exception of His273, were inactive in TA-assay. p53 is a target of several oncogenes found in DNA tumor viruses. We examined the effect of either SV40 T-ag or 55 kDa EIB protein of Ad5 on DNA binding and transactivation by p53 in transformed COS-1 and 293 cell lines, respectively. COS-1 extracts produced strong p53-dependent band-shift of the HBS oligos, that was doubleshifted by anti-p53 but not anti-T-ag antibodies, indicating that T-ag is not part of the complex. COS-1 cells had a high level of WT p53-dependent expression of transfected CAT reporter, indicating the presence of transactivation-competent p53, acting through the HBS element. In human Ad-transformed 293 cells, endogenous p53 was also transactivation competent and capable of DNA binding. In summary, we found efficient transactivation of HBS motif by WT and His273-p53. Studies of COS-1 and 293 cells suggest that a proportion of p53 in transformed cells display wild-type DNA binding and TA properties and that expression of transcriptionally inactive mutant p53 proteins in these cells does not interfere with WT-dependent transactivation.

Mutant p53 proteins have diverse intracellular abilities to oligomerize and activate transcription

Accumulating evidence supports the hypothesis that tumor-suppressor p53 can act as a transcriptional activator. Insertion of high-affinity p53 DNA binding sites upstream of a promoter yields a p53-responsive vector. Chimeric proteins fusing p53 and the GAL4 DNA-binding domain demonstrate the presence of a transcriptional activating domain in the N-terminus of p53. GAL4-p53 chimeras constructed using naturally occurring p53 mutations at either codon 141 (Tyr-141) or 175 (His-175) of p53 had little ability to activate the reporter gene; in contrast, mutations at either codon 248 (Trp-248) or 273 (His-273) produced greater transcriptional activities than did wild-type p53. GAL4 chimeras can be used to analyse interactions between different domains of p53 and between different p53 alleles; a DNA binding site is defined, and a simple measurement can be made of function. We had expected that coexpression of GAL4 chimeras and p53 alleles would squelch transcriptional activation downstream of GAL binding sites. Surprisingly, coexpression of either p53 (Trp-248) or (His-273) with the GALA-p53 (wild-type, His-273, Trp-248, His-175, Tyr-141) effectors conferred an increase in transcriptional activation as compared with the effector alone. Oligomerization of p53 alleles with GAL4-p53 chimeras could underlie this effect, leading to an increase in transcription-activating motifs near the promoter. To test this possibility, we constructed a GAL4-p53 C-terminal chimera with p53 residues 160-393, lacking the transcriptional activating domain but retaining regions believed to be important in p53 oligomerization. Neither GAL4-p53 (C-terminus) nor p53 expression vectors were able to transactivate G5E1B-CAT alone. Both p53 (His-273) and (Trp-248) co-expressed with GAL4-p53 (C-terminus) were able to transactivate the G5E1B-CAT reporter gene; in contrast, p53 (Tyr-141) was not able to activate transcription. p53 (Tyr-141/His-273) behaved as a dominant negative mutant and inhibited the ability of the combination of p53 (His-273) and GAL4-p53 (C-terminus) to stimulate the reporter gene. Double immunoprecipitation by sequentially using GAL4 and p53 antibodies showed that p53 (His-273) and (Tyr-141/His-273), but not p53 (Tyr-141), can efficiently oligomerize in vivo to the C-terminal region of p53. Transcriptional activating function of p53 may be modulated by oligomerization; some mutations, such as His-273 and Trp-248, participate in these functions.(ABSTRACT TRUNCATED AT 400 WORDS)

Localization of the c-ets-2 transactivation domain

The human ets-2 proto-oncogene is one of the homologs of the v-ets gene, found in avian acutely transforming retrovirus E26 (D. Leprince, A. Gegonne, J. Call, C. de Taisne, A. Schneeberger, C. Lagrou, and D. Stehelin, Nature [London] 306:395-397, 1983; M. F. Nunn, P. H. Seeburg, C. Moscovici, and P. H. Duesberg, Nature [London] 306:391-395, 1983), which causes leukemia in chickens. We used the DNA-binding domain of yeast transcriptional activator GAL4 to locate the transactivation region of human ets-2. The transactivation domain of ets-2 was found in the N-terminal part of the protein, which is homologous to ets-1, and can be disrupted by deletion of a stretch of acidic amino acid residues. A transactivation-deficient mutant of ets-2 failed to transform Rat-1 cells and suppressed the transforming activity of coexpressed wild-type ets-2. A mutation in the putative DNA-binding region of ets-2 abolished transforming activity. We show that the motif crucial for ets-2 transactivation capability is necessary for transforming activity in Rat-1 cells. Mutant ets-2 protein that lacks the transactivation domain has a dominant negative effect on transformation by wild-type ets-2. We were unable to detect ets-2-dependent transcriptional regulation of several enhancers containing ets-binding motifs.

Oxytocin receptor subtypes in the pregnant rat myometrium and decidua: pharmacological differentiations

Oxytocin (OT) has a dual action in the uterus: a uterotonic action on myometrial cells and a prostaglandin (PG)-releasing action on endometrial/decidual cells. It had not been determined whether the OT-binding sites or receptors on the myometrial and the endometrial/decidual membranes are of the same type or may represent two subtypes. Our studies presented in this paper show that isolated day 19-22 pregnant rat uterine horns and myometrial tissues (uterine horns with decidual tissues removed) incubated in Kreb's buffer at 37 C released PGF2 alpha in sustained quantities into the bathing medium. OT stimulated PG release over the basal release rate in a dose-dependent manner in the whole uterine horn but not in the myometrial tissue. Two OT antagonists, P[Phe(Me)2,Thr4]ornithine vasotocin (antagonist A) and desGly-NH2(9),d(CH2)5(1)[Tyr(Me)2,Thr4]ornithine vasotocin (antagonist B) were found to have different effects on the PG-releasing action of OT. At antiuterotonic doses, antagonist A had no antagonism of the PG-releasing action of OT. On the contrary, antagonist A was found to stimulate uterine PG release. Antagonist B was a full OT antagonist. At equivalent antiuterotonic doses, antagonist B inhibited both the uterotonic action and the PG-releasing action of OT. These findings suggest that OT-sensitive PGs are synthesized/released principally in the endometrium/decidua. The myometrial uterotonic OT receptors and the endometrial/decidual PG-releasing OT receptors are two distinct subtypes and can be differentiated. The existence of two OT receptor subtypes in the uterus has important implications in the clinical application of OT antagonists as tocolytics for preterm labor. To be efficacious, OT antagonist therapy needs to block both the uterotonic and the PG-releasing action of OT.

[Changes of the binding capacity of sex hormone binding globulin in patients with hyperthyroidism before and after antithyroid therapy]

We studied the change of the binding capacity of the sex hormone binding globulin (SHBG-BC) and correlated it with the serum level of thyroid hormone and sex hormone in 17 patients (10 males and 7 female) with hyperthyroidism before and during the 16 weeks of antithyroid treatment. The serum TT4, TT3, FT4I level and SHBG-BC were significantly elevated before treatment compared to normal adults. After the treatment with antithyroid drugs, serum SHBG-BC decreased significantly at 2nd weeks in female (from 312.9 +/- 39.6 to 205 +/- 18.6 nmol/L, P < 0.05) and at 8th weeks in male (from 155.7 +/- 18.6 to 109.7 +/- 7.9 nmol/L, P < 0.05). It continued to decrease to normal range (78.6 +/- 7.3 vs 65.0 +/- 24.1 nmol/L, P > 0.05) at 8th weeks in female, but was still higher than normal range (107.4 +/- 7.2 vs 41.5 +/- 10.2 nmol/L, P < 0.001) even at 16th weeks in male. The change of SHBG-BC was significantly positively correlated to the serum concentration of TT4, TT3 and FT4I(P < 0.001). In male patients the serum testosterone (T) level decreased from a high level of 41.9 +/- 6.2 nmol/L before treatment to 25.4 +/- 3.4 nmol/L at 8th weeks (P < 0.05) and to 19.8 +/- 2.8 nmol/L at 16 weeks which was in normal range. The decrease of serum T level was also positively correlated to the changes of SHBG-BC (P < 0.0001). The serum estradiol (E2) level of female patients was in the upper normal range before the antithyroid treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

[Comparative studies on the diagnosis of clonorchiasis by IEST and IFAT]

Both immunoenzymatic staining technique (IEST) and indirect fluorescent antibody test. (IFAT) with frozen sections of adult Clonorchis sinensis as antigen were employed for detecting 51 cases with clonorchiasis and 50 healthy persons. The positive rate was 92% with IEST and 88% with IFAT. The results showed no significant statistic difference (P > 0.05). The false positive rates were 2% with the former and 4% with the latter. When sera from 22 cases with acute schistosomiasis, 20 cases with chronic schistosomiasis and 15 cases with paragonimiasis were examined by IEST and IFAT, cross-reactions were 14%, 5% and 0% with IEST, and 14%, 10% and 0% with IFAT, respectively. The results showed that both IEST and IFAT are useful methods for serological diagnosis of clonorchiasis and the antigen on the gut was well demonstrated, while IEST might be more suitable in field surveys.

High prevalence of mutations of the p53 gene in poorly differentiated human thyroid carcinomas

The development and progression of thyroid tumors is signaled by phenotype-specific mutations of genes involved in growth control. Molecular events associated with undifferentiated thyroid cancer are not known. We examined normal, benign, and malignant thyroid tissue for structural abnormalities of the p53 tumor suppressor gene. Mutations were detected by single-strand conformation polymorphisms of PCR-amplified DNA, using primers bracketing the known hot spots on either exons 5, 6, 7, or 8. The prevalence of mutations was as follows: normal thyroid 0/6; follicular adenomas 0/31; papillary carcinomas 0/37; medullary carcinomas 0/2; follicular carcinomas 1/11; anaplastic carcinomas 5/6; thyroid carcinoma cell lines 3/4. Positive cases were confirmed by direct sequencing of the PCR products. All five anaplastic carcinoma tissues and the anaplastic carcinoma cell line ARO had G:C to A:T transitions leading to an Arg to His substitution at codon 273. In both tumors and cell lines, examples of heterozygous and homozygous p53 mutations were identified. The only thyroid carcinoma cell line in which p53 mutations were not detected in exons 5-8 had markedly decreased p53 mRNA levels, suggesting the presence of a structural abnormality of either p53 itself or of some factor controlling its expression. The presence of p53 mutations almost exclusively in poorly differentiated thyroid tumors and thyroid cancer cell lines suggests that inactivation of p53 may confer these neoplasms with aggressive properties, and further loss of differentiated function.