Coil embolization of a fistula from the right inferior phrenic artery to the right pulmonary artery with involvement of further arteries: A rare case report

A 51-year-old female patient was presenting dyspnea for more than a year with no previous lung infections or surgery. Initially, a diagnostic computed tomography was made, showing a rare arterio-arterial malformation between the right inferior phrenic and right pulmonary artery leading into a vascular bundle in the middle lung lobe. Due to the patients' dyspnea and massive extent of malformation, the indication for transcatheter arterial embolization was made. The first transcatheter arterial embolization procedure involved the inferior phrenic and a selective branch of the internal thoracic artery. Interventional angiography as well as computed tomography revealed further extend of the malformation showing a connection of right lateral thoracic, hepatic, and inferior epigastric artery to the fistula. After one month, a second transcatheter arterial embolization of these arteries as well as a second approach of the proximal internal thoracic artery was performed. In the follow-up the patient described a substantial improvement of her dyspnea and showed no signs of infections. A phrenic artery to pulmonary artery fistula is an extremely rare case occurring congenital or acquired. Patients may be asymptomatic or present, among others, dyspnea, hemoptysis, pulmonary infections and congestive heart failure. Symptomatic patients require treatment using transcatheter arterial embolization or surgical resection. The patient had dyspnea and a substantial extent of malformation with possibly complicated clinical course. The recommended less invasive treatment using transcatheter arterial embolization was successfully performed. In conclusion, our patient represented a rare congenital case of systemic and pulmonary artery communication, which we were able to treat sufficiently with coil embolization.

Computed Tomography Radiomics to Differentiate Intrahepatic Cholangiocarcinoma and Hepatocellular Carcinoma

AIMS

Intrahepatic cholangiocarcinoma (iCCA) and hepatocellular carcinoma (HCC) differ in prognosis and treatment. We aimed to non-invasively differentiate iCCA and HCC by means of radiomics extracted from contrast-enhanced standard-of-care computed tomography (CT).

MATERIALS AND METHODS

In total, 94 patients (male, n = 68, mean age 63.3 ± 12.4 years) with histologically confirmed iCCA (n = 47) or HCC (n = 47) who underwent contrast-enhanced abdominal CT between August 2014 and November 2021 were retrospectively included. The enhancing tumour border was manually segmented in a clinically feasible way by defining three three-dimensional volumes of interest per tumour. Radiomics features were extracted. Intraclass correlation analysis and Pearson metrics were used to stratify robust and non-redundant features with further feature reduction by LASSO (least absolute shrinkage and selection operator). Independent training and testing datasets were used to build four different machine learning models. Performance metrics and feature importance values were computed to increase the models' interpretability.

RESULTS

The patient population was split into 65 patients for training (iCCA, n = 32) and 29 patients for testing (iCCA, n = 15). A final combined feature set of three radiomics features and the clinical features age and sex revealed a top test model performance of receiver operating characteristic (ROC) area under the curve (AUC) = 0.82 (95% confidence interval =0.66-0.98; train ROC AUC = 0.82) using a logistic regression classifier. The model was well calibrated, and the Youden J Index suggested an optimal cut-off of 0.501 to discriminate between iCCA and HCC with a sensitivity of 0.733 and a specificity of 0.857.

CONCLUSIONS

Radiomics-based imaging biomarkers can potentially help to non-invasively discriminate between iCCA and HCC.

Increased expression of STAT3 and SOCS3 in placenta from hyperglycemic rats

Signal transducer and activator of transcription 3 (STAT3) is a transcription factor that is activated by interleukin (IL)-6 and IL-10 that generate nearly opposing responses. The suppressor of cytokine signaling 3 (SOCS3) is the negative regulator of STAT3 and plays an important role in the negative regulation of the inflammatory process. Evidence has shown the importance of STAT3 and SOCS3 during implantation and normal pregnancy. However, little is known about the relationship of both factors under hyperglycemic condition. The aim of this study was to evaluate the placenta regions exhibiting immunopositivity for STAT3 and SOCS3 in hyperglycemic rats, as well as correlate these proteins with IL-10 and IL-6 levels. It was observed increased expression of STAT3 at the labyrinth (approximately 47% of increase compared to control) and junctional zone (approximately 32% of increase compared to control) from hyperglycemic placentas. Similar results were observed to SOCS3 (approximately 71% -labyrinth- and 53% -junctional zone- of increase compared to control). The levels of IL-10 were augmented at hyperglycemic placentas (approximately 1.5 fold of increase) and they were positively correlated with the increase of STAT3 at the labyrinth and SOCS at junctional zone. Therefore, under hyperglycemic conditions, the relation between STAT3 and SOCS3 was changed, leading to unbalance of the cytokine profile.

O-GlcNAc Modification During Pregnancy: Focus on Placental Environment

Successful placentation is a key event for fetal development, which commences following embryo implantation into the uterine wall, eliciting decidualization, placentation, and remodeling of blood vessels to provide physiological exchange between embryo-fetus and mother. Several signaling pathways are recruited to modulate such important processes and specific proteins that regulate placental function are a target for the glycosylation with O-linked β-N-acetylglucosamine (O-GlcNAc), or O-GlcNAcylation. This is a reversible post-translational modification on nuclear and cytoplasmic proteins, mainly controlled by O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). O-GlcNAcylation has been implicated as a modulator of proteins, both in physiological and pathological conditions and, more recently, O-GlcNAc has also been shown to be an important modulator in placental tissue. In this mini-review, the interplay between O-GlcNAcylation of proteins and placental function will be addressed, discussing the possible implications of this post-translational modification through placental development and pregnancy.

Evaluation of α-tubulin, detyrosinated α-tubulin, and vimentin in CTCs: identification of the interaction between CTCs and blood cells through cytoskeletal elements

Background

Circulating tumor cells (CTCs) are the major players in the metastatic process. A potential mechanism of cell migration and invasion is the formation of microtentacles in tumor cells. These structures are supported by α-tubulin (TUB), detyrosinated α-tubulin (GLU), and vimentin (VIM). In the current study, we evaluated the expression of those cytoskeletal proteins in CTCs.

Methods

Forty patients with breast cancer (BC) (16 early and 24 metastatic) were enrolled in the study. CTCs were isolated using the ISET platform and stained with the following combinations of antibodies: pancytokeratin (CK)/VIM/TUB and CK/VIM/GLU. Samples were analyzed with the ARIOL platform and confocal laser scanning microscopy.

Results

Fluorescence quantification revealed that the ratios CK/TUB, CK/VIM, and CK/GLU were statistically increased in MCF7 compared with more aggressive cell lines (SKBR3 and MDA-MB-231). In addition, all of these ratios were statistically increased in MCF7 cells compared with metastatic BC patients’ CTCs (p = 0.0001, p = 0.0001, and p = 0.003, respectively). Interestingly, intercellular connections among CTCs and between CTCs and blood cells through cytoskeleton bridges were revealed, whereas microtentacles were increased in patients with CTC clusters. These intercellular connections were supported by TUB, VIM, and GLU. Quantification of the examined molecules revealed that the median intensity of TUB, GLU, and VIM was significantly increased in patients with metastatic BC compared with those with early disease (TUB, 62.27 vs 11.5, p = 0.0001; GLU, 6.99 vs 5.29, p = 0.029; and VIM, 8.24 vs 5.38, p = 0.0001, respectively).

Conclusions

CTCs from patients with BC aggregate to each other and to blood cells through cytoskeletal protrusions, supported by VIM, TUB, and GLU. Quantification of these molecules could potentially identify CTCs related to more aggressive disease.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-0993-z) contains supplementary material, which is available to authorized users.

Dual-energy CT in patients with abdominal malignant lymphoma: impact of noise-optimised virtual monoenergetic imaging on objective and subjective image quality

AIM

To investigate the impact of noise-optimised virtual monoenergetic imaging (VMI+) reconstructions on quantitative and qualitative image parameters in patients with malignant lymphoma at dual-energy computed tomography (DECT) examinations of the abdomen.

MATERIALS AND METHODS

Thirty-five consecutive patients (mean age, 53.8±18.6 years; range, 21-82 years) with histologically proven malignant lymphoma of the abdomen were included retrospectively. Images were post-processed with standard linear blending (M_0.6), traditional VMI, and VMI+ technique at energy levels ranging from 40 to 100 keV in 10 keV increments. Signal-to-noise (SNR) and contrast-to-noise ratios (CNR) were objectively measured in lymphoma lesions. Image quality, lesion delineation, and image noise were rated subjectively by three blinded observers using five-point Likert scales.

RESULTS

Quantitative image quality parameters peaked at 40-keV VMI+ (SNR, 15.77±7.74; CNR, 18.27±8.04) with significant differences compared to standard linearly blended M_0.6 (SNR, 7.96±3.26; CNR, 13.55±3.47) and all traditional VMI series (p<0.001). Qualitative image quality assessment revealed significantly superior ratings for image quality at 60-keV VMI+ (median, 5) in comparison with all other image series (p<0.001). Assessment of lesion delineation showed the highest rating scores for 40-keV VMI+ series (median, 5), while lowest subjective image noise was found for 100-keV VMI+ reconstructions (median, 5).

CONCLUSION

Low-keV VMI+ reconstructions led to improved image quality and lesion delineation of malignant lymphoma lesions compared to standard image reconstruction and traditional VMI at abdominal DECT examinations.

O-linked N-acetyl-glucosamine deposition in placental proteins varies according to maternal glycemic levels

AIMS

Hyperglycemia increases glycosylation with O-linked N-acetyl-glucosamine (O-GlcNAc) contributing to placental dysfunction and fetal growth impairment. Our aim was to determine how O-GlcNAc levels are affected by hyperglycemia and the O-GlcNAc distribution in different placental regions.

MAIN METHODS

Female Wistar rats were divided into the following groups: severe hyperglycemia (>300 mg/dL; n = 5); mild hyperglycemia (>140 mg/dL, at least than two time points during oral glucose tolerance test; n = 7) or normoglycemia (<120 mg/dL; n = 6). At 21 days of pregnancy, placental tissue was collected and processed for morphometry and immunohistochemistry analyses, or properly stored at -80 °C for protein quantification by western blot.

KEY FINDINGS

Placental index was increased only in severe hyperglycemic rats. Morphometric analysis showed increased junctional zone and decreased labyrinth region in placentas exclusively from the severe hyperglycemic group. Proteins targeted by O-GlcNAc were detected in all regions, with increased O-GlcNAc levels in the hyperglycemic group compared to control and mild hyperglycemic rats. Proteins in endothelial and trophoblast cells were the main target for O-GlcNAc. Whereas no changes in O-GlcNAc transferase (OGT) expression were detected, O-GlcNAcase (OGA) expression was reduced in placentas from the severe hyperglycemic group and augmented in placentas from the mild hyperglycemic group, compared with their respective control groups.

SIGNIFICANCE

Placental O-GlcNAc overexpression may contribute to placental dysfunction, as indicated by the placental index. Additionally, morphometric alterations, occurring simultaneously with increased O-GlcNAc accumulation in the placental tissue may contribute to placental dysfunction during hyperglycemia.

Klotho Gene and Protein in Human Placentas According to Birth Weight and Gestational Age

Introduction: Fetal growth restriction may be the consequence of maternal, fetal, or placental factors. The insulin-like growth factors (IGFs) are major determinants of fetal growth, and are expressed in the mother, fetus and placenta in most species. Previously we reported higher placental protein content of IGF-I, IGF-IR, and AKT in small (SGA) compared with those from appropriate for gestational age (AGA) placentas. The protein Klotho, has been reported in placenta and may regulate IGF-I activity. In this study we determined Klotho gene expression and protein immunostaining in term (T-SGA y T-AGA) and preterm (PT-SGA y PT-AGA) human placentas. In addition, we assessed the effect of Klotho on the IGF-IR and AKT activation induced by IGF-I. Methods: Placentas (n = 1 17) from 32 T-SGA (birth weight (BW) = -1.74 ± 0.08 SDS), 37 T-AGA (BW = 0.12 ± 0.12 SDS), 20 PT-SGA (BW = -2.08 ± 0.14 SDS), and 28 PT-AGA (BW = -0.43 ± 0.13 SDS) newborns were collected. mRNA expression by RT-PCR in the chorionic (CP) and basal (BP) plates of the placentas, and the presence of Klotho was evaluated by immunohistochemistry (integral optical density, IOD). In addition, we developed placental explants that were incubated with IGF-I in the presence or absence of Klotho. Results: We found a lower mRNA expression and protein immunoreactivity of Klotho in the CP of SGA (term and preterm) compared with AGA placentas. We also observed a significant reduction in IGF-IR tyrosine activation induced by IGF-I 10 nM when preincubated with 2.0 nM of Klotho (2.4 ± 0.5 arbitrary units vs. 1.3 ± 0.3 AU), and similar results we observed on AKT and ERK_42/44 activation. Conclusion: We describe for the first time that Klotho mRNA and protein varies according to fetal growth and gestational age. In addition, Klotho appears to down-regulate the activation induced by IGF-I on IGF-IR and AKT, suggesting that Klotho may be regulating IGF-I activity in human placentas according to intrauterine fetal growth.

Bile duct ligature in young rats: A revisited animal model for biliary atresia

Biliary atresia leads to cirrhosis in the vast majority of patients and constitutes the first cause of paediatric liver transplantation. Animal models allow us to understand the molecular basis and natural history of diseases. The aim of this study is to describe a surgically created animal model of biliary atresia with emphasis in long-term liver function. Forty-two 3-week-old Sprague-Dawley rats were randomly divided into two groups: bile duct ligature (BDL) and control. The animals were sacrificed on the 2nd, 4th, and 6th postoperative weeks. Blood samples were collected for liver function analysis. The spleen to body weight ratio was determined. Histopathological examination of liver tissue was performed by hematoxylin-eosin and Sirius red staining. Collagen quantification was determined by using colorimetric digital image analysis and was expressed as a percentage of total liver tissue area. Quantitative real-time polymerase chain reaction was performed to analyse gene expression levels of transforming growth factor-β1 (Tgfb1) and apeline (Apln) genes. Statistical analysis was performed where P&lt;0.05 was considered significant. Animals from BDL group developed increasing cholestasis with clinical and laboratory features. Splenomegaly was detected at 4th and 6th week (P&lt;0.05). Histological evaluation of the liver showed ductular reaction, portal fibrosis and bile plugs. Collagen area to total liver tissue area had a median of 2.5% in the control group and 6.5 %, 14.3 % and 37.7 % in BDL rats at 2nd, 4th and 6th weeks respectively (P&lt;0.001). Tgfb1 mRNA expression level was significantly higher at 6th week (P&lt;0.001) in BDL group when compared to control. Apln mRNA expression level was significantly higher at 4th and 6th week (P&lt;0.001) and showed a positive linear correlation (r = 0.975, P&lt;0.05) in BDL group when compared to control. Bile duct ligature in young rats is an animal model that recreates clinical, laboratory, histological and molecular findings of biliary atresia. Bile duct ligature constitutes a good animal model to investigate therapeutic approaches for modifying the progression of liver fibrosis in biliary atresia.

Unique trophoblast stem cell- and pluripotency marker staining patterns depending on gestational age and placenta-associated pregnancy complications

Preeclampsia (PE) and intrauterine growth retardation (IUGR) are rare but severe pregnancy complications that are associated with placental insufficiency often resulting in premature birth. The clinical pathologies are related to gross placental pathologies and trophoblastic deficiencies that might derive from inflammatory processes and oxidative stress injury. The mesenchymal core of placental villi has been identified as a possible niche for trophoblast progenitor cells that are called upon to replenish the injured syncytiotrophoblast layer. These progenitor cells are known to express trophoblast stem cell (CDX2) and pluripotency (SOX2, NANOG and OCT4A) markers, however only little data is available characterizing the expression of these transcription factors beyond the blastocyst stage. We aimed to describe the expression of these factors in healthy 1st and 3rd trimester placentae as well as PE, IUGR and combined PE+IUGR placentae. We analyzed 8 respective samples derived from 1st trimester (elective abortions), and 3rd trimester (healthy controls, PE, IUGR and combined PE+IUGR). We accomplished immunoperoxidase staining to detect the stem cell markers: CDX2 (trophectoderm), SOX2, NANOG and OCT4A (embryonal). Immunoreative scoring was used for objective analyses of staining patterns. All markers display clearly elevated signals in 1st trimester villous samples as compared to healthy 3rd trimester counterparts. Especially CDX2 and NANOG were specific to the cytotrophoblast layer and the mesenchymal core. Specific and differential expression patterns were visible in the villous/extravillous compartment of each placenta-associated pregnancy complication (PE: pan elevated expression; IUGR elevated SOX2 in basal plate; combined PE+IUGR pan loss of expression). Reduction of stem cell transcription factor expression in term placentae indicates temporal regulation, and probably a specific function which is yet to be elucidated. The differential expression patterns within placentae complicated with placenta-associated pregnancy complications indicate that PE, IUGR and combined PE+IUGR are separate entities. It is unclear whether the alterations are the cause or the effect of the clinical pathology.

Analysis of multiple physical parameters for mechanical phenotyping of living cells

Since the cytoskeleton is known to regulate many cell functions, an increasing amount of effort to characterize cells by their mechanical properties has occured. Despite the structural complexity and dynamics of the multicomponent cytoskeleton, mechanical measurements on single cells are often fit to simple models with two to three parameters, and those parameters are recorded and reported. However, different simple models are likely needed to capture the distinct mechanical cell states, and additional parameters may be needed to capture the ability of cells to actively deform. Our new approach is to capture a much larger set of possibly redundant parameters from cells' mechanical measurement using multiple rheological models as well as dynamic deformation and image data. Principal component analysis and network-based approaches are used to group parameters to reduce redundancies and develop robust biomechanical phenotyping. Network representation of parameters allows for visual exploration of cells' complex mechanical system, and highlights unexpected connections between parameters. To demonstrate that our biomechanical phenotyping approach can detect subtle mechanical differences, we used a Microfluidic Optical Cell Stretcher to mechanically stretch circulating human breast tumor cells bearing genetically-engineered alterations in c-src tyrosine kinase activation, which is known to influence reattachment and invasion during metastasis.

Quantitative description of the morphology and ossification center in the axial skeleton of 20-week gestation formalin-fixed human fetuses using magnetic resonance images

OBJECTIVES

Human tissues are usually studied using a series of two-dimensional visualizations of in vivo or cutout specimens. However, there is no precise anatomical description of some of the processes of human fetal development. The purpose of our study is to develop a quantitative description of the normal axial skeleton by means of high-resolution three-dimensional magnetic resonance (MR) images, collected from six normal 20-week-old human fetuses fixed in formaldehyde.

METHODS

Fetuses were collected after spontaneous abortion and subsequently fixed with formalin. They were imaged using a 1.5 T MR scanner with an isotropic spatial resolution of 200 µm. The correct tissue discrimination between ossified and cartilaginous bones was confirmed by comparing the images achieved by MR scans and computerized axial tomographies. The vertebral column was segmented out from each image using a specially developed semi-automatic algorithm.

RESULTS

Vertebral body dimensions and inter-vertebral distances were larger in the lumbar region, in agreement with the beginning of the ossification process from the thoracolumbar region toward the sacral and cephalic ends.

CONCLUSION

In this article, we demonstrate the feasibility of using MR images to study the ossification process in formalin-fixed fetal tissues. A quantitative description of the ossification centers of vertebral bodies and arches is presented.

Loss of PTEN induces microtentacles through PI3K-independent activation of cofilin

Loss of PTEN tumor suppressor enhances metastatic risk in breast cancer, although the underlying mechanisms are poorly defined. We report that homozygous deletion of PTEN in mammary epithelial cells induces tubulin-based microtentacles (McTNs) that facilitate cell reattachment and homotypic aggregation. Treatment with contractility-modulating drugs showed that McTNs in PTEN(-/-) cells are suppressible by controlling the actin cytoskeleton. Because outward microtubule extension is counteracted by actin cortical contraction, increased activity of actin-severing proteins could release constraints on McTN formation in PTEN(-/-) cells. One such actin-severing protein, cofilin, is activated in detached PTEN(-/-) cells that could weaken the actin cortex to promote McTNs. Expression of wild-type cofilin, an activated mutant (S3A), and an inactive mutant (S3E) demonstrated that altering cofilin phosphorylation directly affects McTNs formation. Chemical inhibition of PI3K did not reduce McTNs or inactivate cofilin in PTEN(-/-) cells. Additionally, knock-in expression of the two most common PI3K-activating mutations observed in human cancer patients did not increase McTNs or activate cofilin. PTEN loss and PI3K activation also caused differential activation of the cofilin regulators, LIM-kinase1 (LIMK) and Slingshot-1L (SSH). Furthermore, McTNs were suppressed and cofilin was inactivated by restoration of PTEN in the PTEN(-/-) cells, indicating that both the elevation of McTNs and the activation of cofilin are specific results arising from PTEN loss. These data identify a novel mechanism by which PTEN loss could remodel the cortical actin network to facilitate McTNs that promote tumor cell reattachment and aggregation. Using isogenic MCF-10A PTEN(-/-) and PIK3CA mutants, we have further demonstrated that there are clear differences in activation of cofilin, LIMK and SSH between PTEN loss and PI3K activation, providing a new evidence that these mutations yield distinct cytoskeletal phenotypes, which could have an impact on tumor biology.

Metastatic breast tumors express increased tau, which promotes microtentacle formation and the reattachment of detached breast tumor cells

The cytoskeletal organization of detached and circulating tumor cells (CTCs) is currently not well defined and may provide potential targets for new therapies to limit metastatic tumor spread. In vivo, CTCs reattach in distant tissues by a mechanism that is tubulin-dependent and suppressed by polymerized actin. The cytoskeletal mechanisms that promote reattachment of CTCs match exactly with the mechanisms supporting tubulin microtentacles (McTN), which we have recently identified in detached breast tumor cells. In this study, we aimed to investigate how McTN formation is affected by the microtubule-associated protein, tau, which is expressed in a subset of chemotherapy-resistant breast cancers. We demonstrate that endogenous tau protein localizes to McTNs and is both necessary and sufficient to promote McTN extension in detached breast tumor cells. Tau-induced McTNs increase reattachment of suspended cells and retention of CTCs in lung capillaries. Analysis of patient-matched primary and metastatic tumors reveals that 52% possess tau expression in metastases and 26% display significantly increased tau expression over disease progression. Tau enrichment in metastatic tumors and the ability of tau to promote tumor cell reattachment through McTN formation support a model in which tau-induced microtubule stabilization provides a selective advantage during tumor metastasis.

The estrous cycle modulates small leucine-rich proteoglycans expression in mouse uterine tissues

In the pregnant mouse uterus, small leucine-rich proteoglycans (SLRPs) are drastically remodeled within a few hours after fertilization, suggesting that ovarian hormone levels modulate their synthesis and degradation. In this study, we followed by immunoperoxidase approach, the presence of four members of the SLRP family (decorin, lumican, biglycan, and fibromodulin) in the uterine tissues along the estrous cycle of the mouse. All molecules except fibromodulin, which predominates in the myometrium, showed a striking modulation in their distribution in the endometrial stroma, following the rise in the level of estrogen. Moreover, notable differences in the distribution of SLRPs were observed between superficial and deep stroma, as well as between the internal and external layers of the myometrium. Only biglycan and fibromodulin were expressed in the luminal and glandular epithelia. All four SLRPs were found in cytoplasmic granules of mononucleated cells. The pattern of distribution of the immunoreaction for these molecules in the uterine tissues was found to be estrous cycle-stage dependent, suggesting that these molecules undergo ovarian hormonal control and probably participate in the preparation of the uterus for decidualization and embryo implantation. In addition, this and previous results from our laboratory suggest the existence of two subpopulations of endometrial fibroblasts that may be related to the centrifugal development of the decidua. Anat Rec, 2008. (c) 2008 Wiley-Liss, Inc.

TNF-alpha knockout mice have increased corpora cavernosa relaxation

INTRODUCTION

Erectile dysfunction is considered an early clinical manifestation of vascular disease and an independent risk factor for cardiovascular events associated with endothelial dysfunction and increased levels of pro-inflammatory cytokines. Tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine, suppresses endothelial nitric oxide synthase (eNOS) expression.

AIM

Considering that nitric oxide (NO) is of critical importance in penile erection, we hypothesized that blockade of TNF-alpha actions would increase cavernosal smooth muscle relaxation.

METHODS

In vitro organ bath studies were used to measure cavernosal reactivity in wild type and TNF-alpha knockout (TNF-alpha KO) mice and NOS expression was evaluated by western blot. In addition, spontaneous erections (in vivo) were evaluated by videomonitoring the animals (30 minutes). Collagen and elastin expression were evaluated by Masson trichrome and Verhoff-van Gieson stain reaction, respectively.

MAIN OUTCOME MEASURES

Corpora cavernosa from TNF-alpha KO mice exhibited increased NO-dependent relaxation, which was associated with increased eNOS and neuronal NOS (nNOS) cavernosal expression.

RESULTS

Cavernosal strips from TNF-alpha KO mice displayed increased endothelium-dependent (97.4 +/- 5.3 vs.

CONTROL

76.3 +/- 6.3, %) and nonadrenergic-noncholinergic (93.3 +/- 3.0 vs.

CONTROL

67.5 +/- 16.0; 16 Hz) relaxation compared to control animals. These responses were associated with increased protein expression of eNOS and nNOS (P < 0.05). Sympathetic-mediated (0.69 +/- 0.16 vs.

CONTROL

1.22 +/- 0.22; 16 Hz) as well as phenylephrine-induced contractile responses (1.6 +/- 0.1 vs.

CONTROL

2.5 +/- 0.1, mN) were attenuated in cavernosal strips from TNF-alpha KO mice. Additionally, corpora cavernosa from TNF-alpha KO mice displayed increased collagen and elastin expression. In vivo experiments demonstrated that TNF-alpha KO mice display increased number of spontaneous erections.

CONCLUSION

Corpora cavernosa from TNF-alpha KO mice display alterations that favor penile tumescence, indicating that TNF-alpha plays a detrimental role in erectile function. A key role for TNF-alpha in mediating endothelial dysfunction in ED is markedly relevant since we now have access to anti-TNF-alpha therapies.

Targeting novel microtentacles to reduce the adhesion of circulating tumor cells to blood vessel walls

Abstract #2044

Detached human breast tumor cell lines produce novel protrusions of the plasma membrane that promote reattachment of tumor cells to each other and extracellular matrix. We have termed these protrusions “microtentacles” due to clear mechanistic distinctions from either actin-based filopodia/invadopodia or tubulin-based cilia.&#x2028; &#x2028; Compelling in vivo studies show that a mechanism consistent with microtentacles is responsible for the attachment of circulating tumor cells to blood vessel walls. Human breast tumor cell lines that display a disorganized actin cortex and hallmarks of epithelial-to-mesenchymal transition produce higher frequencies and greater extension of microtentacles. Conversely, some current and proposed tumor drugs that target the cytoskeleton actually increase microtentacles. While many cancer therapies are directed against the process of cell division, it remains important to consider the effects of these drugs on the invasive characteristics of tumor cells. Our current research has determined that microtentacles are composed of coordinated filaments of vimentin and detyrosinated tubulin. Previous studies indicate that elevated levels of vimentin and detyrosinated tubulin in tumors predict poor patient outcome, although the specific mechanisms remain unclear. Time-lapse video microscopy also indicates that the rapid extension and dynamic motion of microtentacles relies on kinesin activation. Again, our results suggest that the kinesin responsible is a conventional kinesin, rather than the mitotic kinesins commonly targeted by cancer therapies. We propose that the independent roles of vimentin, detyrosinated tubulin and kinesin in tumor metastasis could result from their interdependent contributions to microtentacle formation. Since large epithelial tumor cells are often fragmented in narrow capillaries, we are targeting microtentacles to promote the fragmentation of circulating tumor cells in the capillaries of the lung. We are currently using time-lapse confocal microscopy of tumor cells circulating in intact blood vessels and whole-animal optical imaging to define therapies that reduce microtentacle-dependent adhesion of circulating breast tumor cells during metastasis.&#x2028; &#x2028; This image shows circulating tumor cells (red) adhering to the walls of an intact blood vessel (green).

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2044.

Tailoring an HIV-prevention intervention for cocaine injectors and crack users in Porto Alegre, Brazil

Brazil has the second largest number of reported AIDS cases in the world. Porto Alegre, like most other large urban centres in Brazil, has been greatly impacted by an AIDS epidemic driven by high rates of drug use and risky sexual behaviours. While epidemiologic surveillance of HIV/AIDS and treatment initiatives for HIV-infected individuals are well developed in Brazil, comparatively little attention has focused on developing interventions directed toward high-risk populations. Intervention programmes, particularly those tailored for chronic drug users, are lacking. This pilot project successfully adapted and tailored a cognitive behavioural HIV intervention developed in the US to the cultural setting in Porto Alegre. The project established feasibility and acceptability of the approach for targeting risky drug and sexual behaviours among a group of male Brazilian drug users. A sample of 120 male cocaine users was recruited from a public health clinic serving the target population in the city of Porto Alegre. The average age of the participants was 29; they averaged less than 8 years of formal education; and less than half (41%) were married. Lifetime self-reported drug use was high with 93% reporting cocaine use, 87% reporting crack use, and 100% reporting marijuana use. 43% of the sample reported ever injecting drugs. Reports of risky sexual behaviours were similarly elevated. Almost half (45%) tested positive for HIV. Preliminary evidence suggests that intervention acceptability was high among participants. Given the reported high risk sexual and drug use behaviours among these men, HIV interventions must be evaluated and expanded to include this population as well as their sexual partners.

Collagen and tenascin-C expression along the migration pathway of mouse primordial germ cells

Primordial germ cells (PGCs) are the progenitor cells of the vertebrate germ line. These cells originate outside of the embryo and, through separation, migration, and colonization, arrive at the genital ridge, contributing to gonad development. Diverse extracellular matrix molecules are present along the PGC migratory pathway, permitting or inhibiting PGC displacement. Collagens and tenascin form the substratum for in vitro migration of neural crest cells and PGCs. However, little is known about the expression and distribution of these molecules during in situ PGC migration. Using immunohistochemistry, we identified tenascin-C and types I, III, and V collagen along the mouse PGC migration pathway. These molecules were spatiotemporally expressed in basement membranes of hindgut, coelomic epithelia, and mesonephric tubules and mesenchyme throughout the study. Our results complement previous data from our laboratory and contribute to building comprehension of the composition of the mouse PGC migratory pathway extracellular matrix, thereby enhancing understanding of the process.

The terrible triad of the shoulder

This case shows that the terrible triad of the shoulder-anterior dislocation, brachial plexus injury, and rotator cuff tear-can occur in younger populations than previously described. A high index of suspicion for this triad of injury should be maintained, particularly in those young individuals with grossly unstable shoulders. Once axillary nerve function has begun to return, simultaneous repair of all soft tissue injuries can lead to a stable, functional joint.

Differential expression of glycosaminoglycans and proteoglycans in the migratory pathway of the primordial germ cells of the mouse

Primordial germ cells are an embryonic cell line that give rise to gametes in vertebrates. They originate outside the embryo proper and migrate by a well-defined route to the genital ridges. Proteoglycans and glycosaminoglycans have distinctive properties that affect many of the characteristics of the extracellular microenvironment of migratory pathways in a variety of developmental systems. The purpose of this work was to identify the proteoglycans and glycosaminoglycans that are spatially and temporally expressed in the migratory pathway of primordial germ cells. We showed that the expression of proteoglycans and glycosaminoglycans in the primordial germ cells migratory pathway changes according to the different phases of the migratory process. Some molecules such as chondroitin-0-sulfate, decorin, and biglycan are present only in certain phases of the migratory process of primordial germ cells. Heparan sulfate, chondroitin-6-sulfate, versican, perlecan, and syndecan-4, although exhibiting some variation in expression were detected during all phases of the migratory process. Our results indicate that the successive steps of primordial germ cell migration require a coordinated expression of proteoglycans and glycosaminoglycans, that should be present in appropriate levels and in specific areas of the embryo, and that the sequential expression of these extracellular matrix molecules is under a genetic program that appears to be common to a variety of cell types during embryonic development.

Modulation of hyaluronan in the migratory pathway of mouse primordial germ cells

In the present report we followed the distribution of hyaluronan during the phases of separation, migration, and colonization of the primordial germ cell migratory process. Hyaluronan was detected by the use of two cytochemical methods: (1) ruthenium hexammine trichloride (RHT) associated with enzymatic treatment with hyaluronate lyase and (2) a binding specific probe for hyaluronan. After RHT treatment the proteoglycans and/or glycosaminoglycans were observed as a meshwork formed by electron-dense granules connected by thin filaments. After enzymatic digestion, no filaments could be detected in the migratory pathway. Quantitative analysis showed a close correlation between cell migration and the concentration of RHT-positive filaments. It was also shown that high amounts of hyaluronan were expressed in the separation phase and migration phases whereas during the colonization phase the amount of hyaluronan was clearly diminished. This study showed that the presence of primordial germ cells in each compartment of the migratory pathway was always accompanied by a high expression of hyaluronan. These results indicate that hyaluronan is an important molecule in the migratory process, providing the primordial germ cells with a hydrated environment that facilitates their movement toward the genital ridges.

Internal poverty and teen pregnancy

The subjects for the present study were drawn from the female students who participated in the National Education Longitudinal Study (NELS) initial eighth-grade data collection. Adolescent females who later became pregnant were matched on race, birth month, and birth year with adolescent females who did not report a pregnancy. The study examined selected predictor variables from the baseline 1988 wave of data in relation to the outcome variable of pregnancy status. Results indicated a statistically significant difference in locus of control between those females who later became pregnant and those who later did not experience a pregnancy during adolescence. Those who later became pregnant were much more likely to have an external locus of control (p = .0001). Females who later became pregnant were also more likely to have a poorer sense of personal efficacy (p = .0001). Finally, females who later experienced a teen pregnancy had more traditional occupational expectations (p = .006) and lower educational expectations (p = .001) than did those who did not later report a teen pregnancy.

Quasi-equivalence in site-specific recombinase structure and function: crystal structure and activity of trimeric Cre recombinase bound to a three-way Lox DNA junction

The crystal structure of a novel Cre-Lox synapse was solved using phases from multiple isomorphous replacement and anomalous scattering, and refined to 2.05 A resolution. In this complex, a symmetric protein trimer is bound to a Y-shaped three-way DNA junction, a marked departure from the pseudo-4-fold symmetrical tetramer associated with Cre-mediated LoxP recombination. The three-way DNA junction was accommodated by a simple kink without significant distortion of the adjoining DNA duplexes. Although the mean angle between DNA arms in the Y and X structures was similar, adjacent Cre trimer subunits rotated 29 degrees relative to those in the tetramers. This rotation was accommodated at the protein-protein and DNA-DNA interfaces by interactions that are "quasi-equivalent" to those in the tetramer, analogous to packing differences of chemically identical viral subunits at non-equivalent positions in icosahedral capsids. This structural quasi-equivalence extends to function as Cre can bind to, cleave and perform strand transfer with a three-way Lox substrate. The structure explains the dual recognition of three and four-way junctions by site-specific recombinases as being due to shared structural features between the differently branched substrates and plasticity of the protein-protein interfaces. To our knowledge, this is the first direct demonstration of quasi-equivalence in both the assembly and function of an oligomeric enzyme.

Human MCF10A mammary epithelial cells undergo apoptosis following actin depolymerization that is independent of attachment and rescued by Bcl-2

Many tumor cells are impaired in adhesion-regulated apoptosis, which contributes to their metastatic potential. However, suppression of this apoptotic pathway in untransformed cells is not mediated only by adhesion to the extracellular matrix but also through the resulting ability to spread and adopt a distinct morphology. Since cell spreading is dependent on the integrity of the actin microfilament cytoskeleton, we sought to determine if actin depolymerization was sufficient to induce apoptosis, even in the presence of continuous attachment. For this study, we used a human mammary epithelial cell line (MCF10A), which is immortalized but remains adhesion dependent for survival. Treatment of MCF10A cells with latrunculin-A (LA), an inhibitor of actin polymerization, rapidly led to disruption of the actin cytoskeleton and caused cell rounding but preserved attachment. Initiation of apoptosis in LA-treated MCF10A cells was detected by mitochondrial localization of the Bax apoptotic protein, which was prevented by overexpression of Bcl-2. DNA fragmentation and poly(ADP-ribose) polymerase (PARP) cleavage in LA-treated MCF10A cells indicated progression to the execution phase of apoptosis. The MDA-MB-453 cell line, which was derived from a metastatic human mammary tumor, was resistant to PARP cleavage and loss of viability in response to actin depolymerization. Stable overexpression of Bcl-2 in the untransformed MCF10A cells was able to recapitulate the resistance to apoptosis found in the tumor cell line. We demonstrate that inhibition of actin polymerization is sufficient to stimulate apoptosis in attached MCF10A cells, and we present a novel role for Bcl-2 in cell death induced by direct disruption of the actin cytoskeleton.

Sensation seeking needs among 8th and 11th graders: characteristics associated with cigarette and marijuana use

This cross-sectional school-based study explored the relationship between adolescent use of cigarettes and marijuana and the sensation seeking personality factors of (1) Disinhibition and (2) Thrill and Adventure Seeking. The study population included a representative sample of both male and female 8th and 11th graders in the state of Delaware. Analytic methods utilized included correlational analysis and multivariate logistic regression. In the multivariate logistic regression models, the Disinhibition personality factor accounted for cigarette and marijuana using behaviors with odds ratios ranging between 2 and 3. Thrill and Adventure Seeking was not a significant explanatory variable in any of the final multivariate models. Potential confounders (age, gender and race) were considered in all analyses. Of all the two-way interactions assessed, none was significant. The findings from this study utilizing a large general community sample indicate that sensation seeking needs are a potential risk factor for adolescent substance use.

Cryotherapy: an effective modality for decreasing intraarticular temperature after knee arthroscopy

Cryotherapy is a modality commonly used after arthroscopic procedures. We divided 17 patients into two groups after routine knee arthroscopy: 12 patients were immediately treated with ice and 5 control patients were treated without ice for the first hour. In all patients, thermocouple probes were placed intraarticularly into the lateral gutter of the knee. Ice was placed on the operative knees of the treatment group for 2 hours. The control group had no intervention for the 1st hour and then had ice applied for the 2nd hour. Temperatures were continually recorded every minute for 2 hours. The temperature in the treatment group declined significantly, by 2.2 degrees C (95% confidence interval [-3.6 degrees C, -0.72 degrees C]) over the 1st hour and by 0.79 degrees C (95% CI [-1.8 degrees C, 0.18 degrees C]) over the 2nd hour (P = 0.008). The temperature in the control group increased significantly, by 5.0 degrees C (95% CI [2.4 degrees C, 7.5 degrees C]) over the 1st hour (P = 0.006). After ice was applied, the temperature fell significantly, by 4.0 degrees C (95% CI [-8.3 degrees C, 0.26 degrees C]) (P = 0.06). The difference between the temperature decrease in the treatment group and the increase in the control group at 60 minutes was 7.1 degrees C. This is the first rigorously conducted study in human patients that documents a statistically significant decline in intraarticular knee temperature with the application of ice and compression to the skin. The mechanism by which cryotherapy acts must therefore include the cooling effect on the intraarticular environment and synovium.

In vivo selection of RNA-binding peptides from combinatorial libraries

We have used a two step procedure to identify peptides that bind strongly to the Rev-response element (RRE) of HIV. In the first step, RRE-binding peptides were screened from a combinatorial peptide library generated by "randomization" using a small subset of the 20 amino acids. In the second step, one such RRE-binding peptide, RSG-1, was "evolved" into an even stronger RRE-binding peptide using a codon-based mutagenesis procedure. After 2 rounds of evolution, RSG-1.2 bound the RRE with 7-fold higher affinity than wild-type Rev peptide.

Use of radiographic atlases in a mass fatality

In May and June of 1996, a forensic anthropology team from the C.A. Pound Human Identification Laboratory at the University of Florida identified 9 of 10 juveniles from the crash of ValuJet 592. The team relied primarily on a radiographic atlas developed and used by clinical practitioners to determine skeletal age. Postmortem radiographs of the juvenile victims were compared with radiographic standards to determine skeletal age. Skeletal age was then compared to a passenger list indicating the sex, weight, height, and chronological age of each individual. Tentative identifications based on the atlas method were organized into an exclusion matrix. Final identifications were based on this assessment in conjunction with other anthropological data such as appearance and fusion of ossification centers and estimation of stature.

An SH2 domain-containing 5' inositolphosphatase inhibits insulin-induced GLUT4 translocation and growth factor-induced actin filament rearrangement

Tyrosine kinase receptors lead to rapid activation of phosphatidylinositol 3-kinase (PI3 kinase) and the subsequent formation of phosphatidylinositides (PtdIns) 3,4-P2 and PtdIns 3,4, 5-P3, which are thought to be involved in signaling for glucose transporter GLUT4 translocation, cytoskeletal rearrangement, and DNA synthesis. However, the specific role of each of these PtdIns in insulin and growth factor signaling is still mainly unknown. Therefore, we assessed, in the current study, the effect of SH2-containing inositol phosphatase (SHIP) expression on these biological effects. SHIP is a 5' phosphatase that decreases the intracellular levels of PtdIns 3,4,5-P3. Expression of SHIP after nuclear microinjection in 3T3-L1 adipocytes inhibited insulin-induced GLUT4 translocation by 100 +/- 21% (mean +/- the standard error) at submaximal (3 ng/ml) and 64 +/- 5% at maximal (10 ng/ml) insulin concentrations (P < 0.05 and P < 0.001, respectively). A catalytically inactive mutant of SHIP had no effect on insulin-induced GLUT4 translocation. Furthermore, SHIP also abolished GLUT4 translocation induced by a membrane-targeted catalytic subunit of PI3 kinase. In addition, insulin-, insulin-like growth factor I (IGF-I)-, and platelet-derived growth factor-induced cytoskeletal rearrangement, i.e., membrane ruffling, was significantly inhibited (78 +/- 10, 64 +/- 3, and 62 +/- 5%, respectively; P < 0.05 for all) in 3T3-L1 adipocytes. In a rat fibroblast cell line overexpressing the human insulin receptor (HIRc-B), SHIP inhibited membrane ruffling induced by insulin and IGF-I by 76 +/- 3% (P < 0.001) and 68 +/- 5% (P < 0.005), respectively. However, growth factor-induced stress fiber breakdown was not affected by SHIP expression. Finally, SHIP decreased significantly growth factor-induced mitogen-activated protein kinase activation and DNA synthesis. Expression of the catalytically inactive mutant had no effect on these cellular responses. In summary, our results show that expression of SHIP inhibits insulin-induced GLUT4 translocation, growth factor-induced membrane ruffling, and DNA synthesis, indicating that PtdIns 3,4,5-P3 is the key phospholipid product mediating these biological actions.

The functional role of CrkII in actin cytoskeleton organization and mitogenesis

Crk is a member of a family of adapter proteins predominantly composed of Src homology 2 and 3 domains, whose role in signaling pathways is presently unclear. Using an in situ electroporation system which permits the introduction of glutathione S-transferase (GST) fusion proteins into cells, we found that c-CrkII bound to p130(cas), but not to paxillin in serum-starved rat-1 fibroblasts overexpressing the human insulin receptor (HIRc cells) in vivo. 17 nM insulin stimulation dissociated the binding of c-CrkII to p130(cas), whereas 13 nM insulin-like growth factor-I, 16 nM epidermal growth factor (EGF), and 10% serum each showed little or no effect. We found that stress fiber formation is consistent with a change in the p130(cas).c-CrkII interactions before and after growth factor stimulation. Microinjection of either GST-Crk-SH2 or -Crk-(N)SH3 domains, or anti-Crk antibody each inhibited stress fiber formation before and after insulin-like growth factor-I, EGF, and serum stimulation. Insulin stimulation by itself caused stress fiber breakdown and there was no additive effect of microinjection. Microinjection of anti-p130(cas) antibody also blocked stress fiber formation in quiescent cells. Microinjection of the Crk-inhibitory reagents also inhibited DNA synthesis after insulin-like growth factor-I, EGF, and serum stimulation, but not after insulin. These data suggest that the complex containing p130(cas).c-CrkII may play a crucial role in actin cytoskeleton organization and in anchorage-dependent DNA synthesis.

Microsatellite instability in sarcomas

BACKGROUND

Microsatellite instability (MIN) has been studied in a variety of carcinomas and gynecologic sarcomas, but never in musculoskeletal sarcomas.

METHODS

We evaluated 16 skeletal and soft tissue sarcomas at nine genetic loci from chromosomal regions 1q, 5q, 7q, 12p, 13q, 17p, 19q, and two at 11p--all potential regions of interest regarding musculoskeletal sarcomas.

RESULTS

MIN was identified at one or more loci in seven of the cancers studied (44%). Three tumors had more than one locus with MIN and one tumor, a high-grade osteogenic sarcoma, had five of nine loci positive for MIN.

CONCLUSION

These results indicate that musculoskeletal sarcomas show instability in areas inside and outside the loci of known oncogenes. Areas of mismatch repair, as heralded by MIN, may contribute to the vast heterogeneity of these neoplasms.

Spatial memory in young and older adults: environmental support and contextual influences at encoding and retrieval

Previous studies have demonstrated the existence of an "unequal facilitation" effect in spatial memory. In those experiments, the provision of appropriate environmental support for recall was shown to enhance the recall performance of older adults more than that of young adults. In some cases, this process resulted in parity of performance between the two age groups. The present study evaluated the relative contribution of environmental support to the unequal facilitation effect at encoding and retrieval in a spatial memory task. Results, indicate that, although the provision of environmental support at both encoding and retrieval is necessary for optimal recall across the adult life span, the primary influence of such support for recall in the elderly derives from its presence at encoding.

The small guanosine triphosphate-binding protein Rab4 is involved in insulin-induced GLUT4 translocation and actin filament rearrangement in 3T3-L1 cells

Insulin's stimulation of glucose transport involves the translocation of vesicles containing the glucose transporter GLUT4 to the plasma membrane. Small GTP-binding proteins have been implicated in the regulation of vesicular traffic. We studied the effects of microinjection of wild-type Rab4 glutathione S-transferase fusion protein (WT Rab4), a GTP-binding defective mutant (Rab4 N121I), a guanosine triphosphatase-defective mutant (Rab4 Q67L), and a Rab4 antibody on insulin-induced GLUT4 translocation in 3T3-L1 adipocytes. Microinjection of Rab4 N121I and Rab4 antibodies had no effect on basal GLUT4 staining, but inhibited insulin-induced GLUT4 translocation by 50% compared with that in control IgG-injected cells. WT Rab4 and Rab4 Q67L microinjection had no effect on either basal or insulin-induced GLUT4 translocation. Premixing and coinjection of the Rab4 antibody with WT Rab4 almost completely abolished its inhibitory effect on insulin-induced GLUT4 translocation. In contrast, microinjection of an antibody directed against the highly conserved region of Rab3 proteins had no effect on insulin-induced GLUT4. These results point to a direct role of Rab4 in insulin-induced GLUT4 translocation, and that this effect is dependent on nucleotide binding to the protein. We also studied the effect of microinjection of the same proteins on insulin-induced actin filament rearrangement (membrane ruffling) in the same cell line. Microinjection of Rab4 N121I and Rab4 antibodies inhibited insulin-induced membrane ruffling by 40%, whereas WT Rab4 or a Rab3 antibody injection had no effect on cytoskeletal rearrangement. In summary, 1) Rab4 is a necessary component of the insulin/GLUT4 translocation signaling pathway; 2) the function of Rab4 in this pathway requires GTP binding; 3) Rab4 also participates in the process of insulin-induced membrane ruffling; and 4) Rab3 proteins do not seem to be involved in these processes.

Molding a peptide into an RNA site by in vivo peptide evolution

Short peptides corresponding to the arginine-rich domains of several RNA-binding proteins are able to bind to their specific RNA sites with high affinities and specificities. In the case of the HIV-1 Rev-Rev response element (RRE) complex, the peptide forms a single alpha-helix that binds deeply in a widened, distorted RNA major groove and makes a substantial set of base-specific and backbone contacts. Using a reporter system based on antitermination by the bacteriophage lambda N protein, it has been possible to identify novel arginine-rich peptides from combinatorial libraries that recognize the RRE with affinities and specificities similar to Rev but that appear to bind in nonhelical conformations. Here we have used codon-based mutagenesis to evolve one of these peptides, RSG-1, into an even tighter binder. After two rounds of evolution, RSG-1.2 bound the RRE with 7-fold higher affinity and 15-fold higher specificity than the wild-type Rev peptide, and in vitro competition experiments show that RSG-1.2 completely displaces the intact Rev protein from the RRE at low peptide concentrations. By fusing RRE-binding peptides to the activation domain of HIV-1 Tat, we show that the peptides can deliver Tat to the RRE site and activate transcription in mammalian cells, and more importantly, that the fusion proteins can inhibit the activity of Rev in chloramphenicol acetyltransferase reporter assays. The evolved peptides contain proline and glutamic acid mutations near the middle of their sequences and, despite the presence of a proline, show partial alpha-helix formation in the absence of RNA. These directed evolution experiments illustrate how readily complex peptide structures can be evolved within the context of an RNA framework, perhaps reflecting how early protein structures evolved in an "RNA world."

Localization of p21-activated kinase 1 (PAK1) to pinocytic vesicles and cortical actin structures in stimulated cells

The mechanisms through which the small GTPases Rac1 and Cdc42 regulate the formation of membrane ruffles, lamellipodia, and filopodia are currently unknown. The p21-activated kinases (PAKs) are direct targets of active Rac and Cdc42 which can induce the assembly of polarized cytoskeletal structures when expressed in fibroblasts, suggesting that they may play a role in mediating the effects of these GTPases on cytoskeletal dynamics. We have examined the subcellular localization of endogenous PAK1 in fibroblast cell lines using specific PAK1 antibodies. PAK1 is detected in submembranous vesicles in both unstimulated and stimulated fibroblasts that colocalize with a marker for fluid-phase uptake. In cells stimulated with PDGF, in v-Src-transformed fibroblasts, and in wounded cells, PAK1 redistributed into dorsal and membrane ruffles and into the edges of lamellipodia, where it colocalizes with polymerized actin. PAK1 was also colocalized with F-actin in membrane ruffles extended as a response to constitutive activation of Rac1. PAK1 appears to precede F-actin in translocating to cytoskeletal structures formed at the cell periphery. The association of PAK1 with the actin cytoskeleton is prevented by the actin filament-disrupting agent cytochalasin D and by the phosphatidylinositol 3-kinase inhibitor wortmannin. Co-immunoprecipitation experiments demonstrate an in vivo interaction of PAK1 with filamentous (F)-actin in stimulated cells. Microinjection of a constitutively active PAK1 mutant into Rat-1 fibroblasts overexpressing the insulin receptor (HIRcB cells) induced the formation of F-actin- and PAK1-containing structures reminiscent of dorsal ruffles. These data indicate a close correlation between the subcellular distribution of endogenous PAK1 and the formation of Rac/Cdc42-dependent cytoskeletal structures and support an active role for PAK1 in regulating cortical actin rearrangements.

The amino terminus of insulin-responsive aminopeptidase causes Glut4 translocation in 3T3-L1 adipocytes

The insulin-responsive aminopeptidase (IRAP) is a constituent of the vesicles that contain the insulin-regulated glucose transporter (Glut4). Like Glut4, IRAP translocates to the cell surface in response to insulin. Microinjection into 3T3-L1 adipocytes of a glutathione S-transferase (GST) fusion protein containing the cytosolic portion of IRAP (GST-IRAP-(1-109)), resulted in translocation of Glut4 to the cell surface. Immunostaining of 3T3-L1 adipocytes for Glut4 showed that the percentage of cells with substantial cell surface Glut4 was 10% in unstimulated cells, 8% following injection of GST, and 27% following injection of GST-IRAP-(1-109). Increased cell surface Glut4 occurred within 5-10 min following injection and was maintained for at least 4 h. A fusion protein containing only 28 amino acids from IRAP (GST-IRAP-(55-82)) was as effective in increasing cell surface Glut4 as stimulation with 100 nM insulin (44% versus 43%, respectively). In contrast to insulin-stimulated Glut4 translocation, the redistribution of Glut4 following injection of GST-IRAP-(55-82) was not blocked by wortmannin or co-injection with a SH2 domain from the regulatory subunit of phosphatidylinositol 3-kinase. These data suggest that the amino terminus of IRAP interacts with a retention/sorting protein that also regulates the distribution of Glut4 in insulin-responsive cells.

Social factors predicting postpartum choice of Norplant among African-American and non-Hispanic white adolescents

PURPOSE

This study was designed to determine the factors associated with Norplant choice for postpartum teens.

METHODS

A total of 151 teenagers, ages 12-20 years, who delivered at the Medical Center of Delaware from July to December 1992, were offered insertion of Norplant within 48 h postpartum. A structured interview was conducted in the postpartum period after nondirective counseling sessions including a physical demonstration using anatomical models of various contraceptive methods. Student's t-tests, chi-square, and multivariate analyses were used.

RESULTS

Eighty-six teenagers were African-American (mean age = 17.3 +/- 1.9 years) and 65 non-Hispanic white (NHW) (mean age = 18.3 +/- 1.5 years). The NHW teenagers were older (p < 0.001); the African-American teenagers were more likely to have Medicaid (49% vs. 14%; p < 0.001) and to have one or more friends who use Norplant (62% vs. 34%; p < 0.001). In multivariate analyses, NHW teenagers were more likely to choose Norplant if they had discussed their choice with a parent or guardian [adjusted odds ratio (AOR) = 14.6, 95% confidence interval (CI), 2.12-100.57]; had Medicaid funding (AOR = 12.1; 95% (CI), 10.6-91.34); and had any friends who used Norplant (AOR = 6.3; 95% (CI), 1.38-28.40). However, for African-American teenagers, the strongest predictor for choice of Norplant was number of prior children delivered. After two deliveries, there was a better than four-fold likelihood (AOR = 4.8; 95% (CI), 1.47-15.94) that African-American teenagers would choose Norplant. For the African-American teenagers, parental discussion, Medicaid status, and friends' use of Norplant were not as important as family size, but far greater percentages of the African-American teenagers had access to Medicaid funding and peers who used Norplant.

CONCLUSIONS

NHW and African-American teenagers choose Norplant for different reasons. Lack of funding may have been a barrier to choosing Norplant. Discussions with parents and friends have a positive influence on choosing Norplant for NHW teenagers. African-American teenagers were more likely than NHW to have Medicaid coverage, and more frequently choose Norplant if the current birth was their third child.

The proto-oncogene product p120(cbl) links c-Src and phosphatidylinositol 3'-kinase to the integrin signaling pathway

Integrin-mediated cell adhesion triggers intracellular signaling cascades, including tyrosine phosphorylation of intracellular proteins. We show in this report that p120(cbl) (Cbl), the 120-kDa c-cbl proto-oncogene product, becomes tyrosine-phosphorylated during integrin-mediated macrophage cell adhesion to extracellular matrix substrata and anti-integrin antibodies. This tyrosine phosphorylation does not occur when cells attach to polylysine, to which cells adhere in a nonspecific fashion. It also does not take place when adhesion-induced reorganization of the cytoskeleton is inhibited with cytochalasin D. In contrast to the rapid and transient tyrosine phosphorylation of Cbl by CSF-1 stimulation, tyrosine phosphorylation of Cbl by cell attachment was gradual and persistent. Tyrosine-phosphorylated Cbl was found to form complexes with the SH2 domain-containing signaling proteins Src and phosphatidylinositol 3-kinase; in vitro kinase assays demonstrated that these kinases were active in the Cbl complexes following integrin ligand binding. Furthermore, Cbl was found to translocate to the plasma membrane in response to cell adhesion to fibronectin. These observations suggest that Cbl serves as a docking protein and may transduce signals to downstream signaling pathways following integrin-mediated cell adhesion in macrophages.

Phosphatidylinositol 3-kinase is necessary and sufficient for insulin-stimulated stress fiber breakdown

Rat-1 fibroblasts overexpressing the human insulin receptor undergo rapid actin rearrangement in response to insulin. Breakdown of stress fibers present in quiescent cells is followed by transient membrane ruffling and a return of stress fibers. We investigated the signaling pathways that mediate this insulin-stimulated reorganization of the actin cytoskeleton, which was visualized with rhodamine-phalloidin. Treatment of cells with the phosphatidylinositol 3-kinase (PI3-kinase) inhibitor wortmannin prevented insulin action at the preliminary step of stress fiber breakdown. Cellular microinjection of a polyclonal antibody directed against the p85 subunit of PI3-kinase as well as a purified recombinant p85-SH2 domain protein also inhibited actin reorganization. Transient expression of a constitutively active form of PI3-kinase (p110*) was sufficient to cause both stress fiber breakdown and membrane ruffling in the absence of insulin. Microinjection of a polyclonal anti-Shc antibody or dominant negative N17-Ras protein did not affect actin dynamics, and although constitutively active V12-Ras caused modest cytoskeletal reorganization, this effect was blocked by pretreatment with wortmannin. In summary, activation of PI3-kinase is necessary and sufficient to stimulate actin rearrangement, indicating that PI3-kinase may initiate the only signaling cascade required for insulin to induce cytoskeletal restructuring.

Evidence for an insulin receptor substrate 1 independent insulin signaling pathway that mediates insulin-responsive glucose transporter (GLUT4) translocation

Interaction of the activated insulin receptor (IR) with its substrate, insulin receptor substrate 1 (IRS-1), via the phosphotyrosine binding domain of IRS-1 and the NPXY motif centered at phosphotyrosine 960 of the IR, is important for IRS-1 phosphorylation. We investigated the role of this interaction in the insulin signaling pathway that stimulates glucose transport. Utilizing microinjection of competitive inhibitory reagents in 3T3-L1 adipocytes, we have found that disruption of the IR/IRS-1 interaction has no effect upon translocation of the insulin-responsive glucose transporter (GLUT4). The activity of these reagents was demonstrated by their ability to block insulin stimulation of two distinct insulin bioeffects, membrane ruffling and mitogenesis, in 3T3-L1 adipocytes and insulin-responsive rat 1 fibroblasts. These data suggest that phosphorylated IRS-1 is not an essential component of the metabolic insulin signaling pathway that leads to GLUT4 translocation, yet it appears to be required for other insulin bioeffects.

Activated phosphatidylinositol 3-kinase is sufficient to mediate actin rearrangement and GLUT4 translocation in 3T3-L1 adipocytes

Insulin stimulation of 3T3-L1 adipocytes causes rapid translocation of actin and the GLUT4 glucose transporter to the plasma membrane. Both processes depend on the activity of phosphatidylinositol 3-kinase. Using single cell microinjection, we have transiently expressed a constitutively activated mutant of phosphatidylinositol 3-kinase, p110*, in 3T3-L1 adipocytes. Fluorescent detection of GLUT4 protein and actin within these cells demonstrates that expression of p110* is sufficient to cause translocation of GLUT4 to the plasma membrane and the formation of actin membrane ruffles. These effects are inhibited by wortmannin in the p110*-expressing cells, indicating that the phosphatidylinositol 3-kinase activity of the protein is required. Overexpression of an identical protein containing a point mutation in the kinase domain, p110*Deltakin, was incapable of mediating either action, confirming that neither the microinjection process nor a nonspecific effect of the protein was responsible for the observed effects. These data suggest that although insulin is capable of inducing numerous signaling pathways, the isolated activation of phosphatidylinositol 3-kinase can initiate the signaling cascade leading to both actin rearrangement and GLUT4 translocation in the absence of insulin stimulation.

Selection of RNA-binding peptides in vivo

Many priniciples of sequence-specific DNA recognition have been established over the past decade, largely from structural studies of protein-DNA and drug-DNA complexes. On the basis of these principles, it has been possible to design or select variants of known structural motifs, including zinc-fingers and minor groove-binding drugs, that bind desired sequences. Here we describe a strategy, based on transcriptional termination in bacteria, to identify specific RNA-binding peptides using the arginine-rich RNA-binding motif as a framework. Peptides were isolated from two combinatorial libraries that bind tightly and specifically to the Rev response element of HIV. It appears that alpha-helical peptides resembling Rev were selected from one library whereas new peptides that probably do not form helices were selected from the other, suggesting that the arginine-rich motif may be a particularly versatile framework for recognizing RNA structures.

Psychoactive medication, alcohol use, and falls among older adults

The purposes of this study were to determine: (1) the prevalence of psychoactive medication and alcohol use and (2) the relationship among psychoactive medications, alcohol use, and falls in a sample of 1028 independently living women and men, aged 55 and older. Twenty-six percent of the sample reported falling, 28% were taking one or more psychoactive drugs, and 38% drank alcohol during the past year. Analyses with logistic regression indicate that predictors of falls were psychoactive drug use, age, and number of illnesses. Living alone, frequency of alcohol use, and gender were not significant predictors.

Residential drug abuse treatment research: are conventional control designs appropriate for assessing treatment effectiveness?

There has been renewed interest in residential drug abuse treatment research since the late 1980s. Earlier research employed control group designs. This article argues that for today's treatment research, the applicability of control groups created by either matched groups or by random sampling is limited. Four difficulties with control group designs are (1) client differences make assembling matched treatment and control groups untenable, (2) implementing random designs is practically impossible in field research, (3) there are ethical, political, and legal dilemmas in withholding treatment from a control group, and (4) randomly selected client populations will behave differently from the more realistic treatment circumstance involving client populations who are selected based on need and motivation. A more applicable perspective for drug abuse treatment research than the control group design needs to recognize that the client influences the treatment as well as that the treatment influences the client. Also, it must be understood that most clients view residential treatment as only one aspect of their life. Most importantly, individual differences must be taken into account when predicting outcome. A perspective that incorporates these concepts can use client history or baseline as its no-treatment comparative condition, and make use of multivariate analyses to help account for many other influences on outcome.

Assessment of a multistage therapeutic community for drug-involved offenders

A multistage therapeutic community (TC) treatment program has been instituted in the Delaware correctional system. Components in place long enough to provide follow-up data consist of a TC in prison and a "transitional" TC outside the prison for parolees. Baseline data at release from prison, and outcome data six months after release were analyzed for 457 respondents. A group who had participated in neither of the TCs was compared to groups who had participated in the TC in prison only, the transitional TC only, or both TCs. The latter two groups had significantly lower rates of drug relapse and criminal recidivism, even when adjusted for other risk factors. There was also a reduction for the prison TC group, although more modest and statistically significant only when adjusted for baseline differences. Outcome benefits of the TC participation were also found for behaviors affecting the risk of HIV infection. The results support the efficacy of a multistage TC program and the importance of the transitional TC as a component.