[Predictive value of net water uptake with respect to early neurological improvement after endovascular treatment in patients with acute anterior circulation large vessel occlusion stroke]

Objective: To investigate the value of net water uptake (NWU) for predicting early neurological improvement (ENI) after endovascular treatment in patients with acute anterior circulation large vessel occlusion stroke. Methods: A case-control study. A total of 132 patients (80 men, 52 women, median age 68 years) with acute anterior circulation large vessel occlusive stroke receiving endovascular treatment were retrospectively analyzed at Jinling Hospital from October 2014 to September 2019. Patients were divided into two groups based on the occurrence of ENI, which was defined as either an improvement of NIHSS score of ≥4 points, or an NIHSS score of 0 or 1 at 24 hours after endovascular treatment. The rank sum test, Chi square test, and other methods were used to compare differences in baseline characteristics between the two groups. Logistic regression analysis was used to investigate independent predictors of postoperative ENI. Receiver operating characteristic curve analysis used to assess the capacity of NWU to predict ENI. Results: Of the 132 patients in the study, ENI occurred in 47 and did not occur in 85. In multivariate logistic regression analysis age [odds ratio (OR)=0.940, 95% confidence interval (CI) 0.903-0.979, P=0.003], time from stroke onset to puncture (OR=0.995, 95%CI 0.991-0.999, P=0.025), time from puncture to recanalization/end of operation (OR=0.985, 95%CI 0.974-0.996, P=0.007), NWU (OR=0.762, 95%CI 0.620-0.937, P=0.010), and mTICI (OR=1.644, 95%CI 1.043-2.590, P=0.032) were predictive factors for ENI. Receiver operating characteristic curve analysis indicated that NWU could effectively predict ENI (area under the curve=0.642, 95%CI 0.543-0.741, P=0.007), and prediction accuracy was improved when it was combined with other clinical parameters. Conclusion: NWU is an independent predictor of ENI in patients with acute anterior circulation large vessel occlusive stroke undergoing endovascular treatment.

Targeting a xenobiotic transporter to ameliorate vincristine-induced sensory neuropathy

Vincristine is a widely used chemotherapeutic drug for the treatment of multiple malignant diseases that causes a dose-limiting peripheral neurotoxicity. There is no clinically effective preventative treatment for vincristine-induced sensory peripheral neurotoxicity (VIPN), and mechanistic details of this side effect remain poorly understood. We hypothesized that VIPN is dependent on transporter-mediated vincristine accumulation in dorsal root ganglion neurons. Using a xenobiotic transporter screen, we identified OATP1B3 as a neuronal transporter regulating the uptake of vincristine. In addition, genetic or pharmacological inhibition of the murine orthologue transporter OATP1B2 protected mice from various hallmarks of VIPN - including mechanical allodynia, thermal hyperalgesia, and changes in digital maximal action potential amplitudes and neuronal morphology - without negatively affecting plasma levels or antitumor effects of vincristine. Finally, we identified α-tocopherol from an untargeted metabolomics analysis as a circulating endogenous biomarker of neuronal OATP1B2 function, and it could serve as a companion diagnostic to guide dose selection of OATP1B-type transport modulators given in combination with vincristine to prevent VIPN. Collectively, our findings shed light on the fundamental basis of VIPN and provide a rationale for the clinical development of transporter inhibitors to prevent this debilitating side effect.

TP-0903 Is Active in Preclinical Models of Acute Myeloid Leukemia with TP53 Mutation/Deletion

Acute myeloid leukemia (AML) with mutations in the tumor suppressor gene TP53 confers a dismal prognosis with 3-year overall survival of <5%. While inhibition of kinases involved in cell cycle regulation induces synthetic lethality in a variety of TP53 mutant cancers, this strategy has not been evaluated in mutant TP53 AML. Previously, we demonstrated that TP-0903 is a novel multikinase inhibitor with low nM activity against AURKA/B, Chk1/2, and other cell cycle regulators. Here, we evaluated the preclinical activity of TP-0903 in TP53 mutant AML cell lines, including a single-cell clone of MV4-11 containing a TP53 mutation (R248W), Kasumi-1 (R248Q), and HL-60 (TP 53 null). TP-0903 inhibited cell viability (IC50, 12−32 nM) and induced apoptosis at 50 nM. By immunoblot, 50 nM TP-0903 upregulated pChk1/2 and pH2AX, suggesting induction of DNA damage. The combination of TP-0903 and decitabine was additive in vitro, and in vivo significantly prolonged median survival compared to single-agent treatments in mice xenografted with HL-60 (vehicle, 46 days; decitabine, 55 days; TP-0903, 63 days; combination, 75 days) or MV4-11 (R248W) (51 days; 62 days; 81 days; 89 days) (p < 0.001). Together, these results provide scientific premise for the clinical evaluation of TP-0903 in combination with decitabine in TP53 mutant AML.

MATE1 Deficiency Exacerbates Dofetilide-Induced Proarrhythmia

Dofetilide is a rapid delayed rectifier potassium current inhibitor widely used to prevent the recurrence of atrial fibrillation and flutter. The clinical use of this drug is associated with increases in QTc interval, which predispose patients to ventricular cardiac arrhythmias. The mechanisms involved in the disposition of dofetilide, including its movement in and out of cardiomyocytes, remain unknown. Using a xenobiotic transporter screen, we identified MATE1 (SLC47A1) as a transporter of dofetilide and found that genetic knockout or pharmacological inhibition of MATE1 in mice was associated with enhanced retention of dofetilide in cardiomyocytes and increased QTc prolongation. The urinary excretion of dofetilide was also dependent on the MATE1 genotype, and we found that this transport mechanism provides a mechanistic basis for previously recorded drug-drug interactions of dofetilide with various contraindicated drugs, including bictegravir, cimetidine, ketoconazole, and verapamil. The translational significance of these observations was examined with a physiologically-based pharmacokinetic model that adequately predicted the drug-drug interaction liabilities in humans. These findings support the thesis that MATE1 serves a conserved cardioprotective role by restricting excessive cellular accumulation and warrant caution against the concurrent administration of potent MATE1 inhibitors and cardiotoxic substrates with a narrow therapeutic window.

Kidney toxicity of the BRAF-kinase inhibitor vemurafenib is driven by off-target ferrochelatase inhibition

A multitude of disease and therapy related factors drive the frequent development of kidney disorders in cancer patients. Along with chemotherapy, the newer targeted therapeutics can also cause kidney dysfunction through on and off-target mechanisms. Interestingly, among the small molecule inhibitors approved for the treatment of cancers that harbor BRAF-kinase activating mutations, vemurafenib can trigger tubular damage and acute kidney injury. BRAF is a proto-oncogene involved in cell growth. To investigate the underlying mechanisms, we developed cell culture and mouse models of vemurafenib kidney toxicity. At clinically relevant concentrations vemurafenib induces cell-death in transformed and primary mouse and human kidney tubular epithelial cells. In mice, two weeks of daily vemurafenib treatment causes moderate acute kidney injury with histopathological characteristics of kidney tubular epithelial cells injury. Importantly, kidney tubular epithelial cell-specific BRAF gene deletion did not influence kidney function under normal conditions or alter the severity of vemurafenib-associated kidney impairment. Instead, we found that inhibition of ferrochelatase, an enzyme involved in heme biosynthesis contributes to vemurafenib kidney toxicity. Ferrochelatase overexpression protected kidney tubular epithelial cells and conversely ferrochelatase knockdown increased the sensitivity to vemurafenib-induced kidney toxicity. Thus, our studies suggest that vemurafenib-associated kidney tubular epithelial cell dysfunction and kidney toxicity is BRAF-independent and caused, in part, by off-target ferrochelatase inhibition.

Influence of YES1 Kinase and Tyrosine Phosphorylation on the Activity of OCT1

Organic cation transporter 1 (OCT1) is a transporter that regulates the hepatic uptake and subsequent elimination of diverse cationic compounds. Although OCT1 has been involved in drug-drug interactions and causes pharmacokinetic variability of many prescription drugs, details of the molecular mechanisms that regulate the activity of OCT1 remain incompletely understood. Based on an unbiased phospho-proteomics screen, we identified OCT1 as a tyrosine-phosphorylated transporter, and functional validation studies using genetic and pharmacological approaches revealed that OCT1 is highly sensitive to small molecules that target the protein kinase YES1, such as dasatinib. In addition, we found that dasatinib can inhibit hepatic OCT1 function in mice as evidenced from its ability to modulate levels of isobutyryl L-carnitine, a hepatic OCT1 biomarker identified from a targeted metabolomics analysis. These findings provide novel insight into the post-translational regulation of OCT1 and suggest that caution is warranted with polypharmacy regimes involving the combined use of OCT1 substrates and kinase inhibitors that target YES1.

Regulation of OATP1B1 Function by Tyrosine Kinase-mediated Phosphorylation

PURPOSE

OATP1B1 (SLCO1B1) is the most abundant and pharmacologically relevant uptake transporter in the liver and a key mediator of xenobiotic clearance. However, the regulatory mechanisms that determine OATP1B1 activity remain uncertain, and as a result, unexpected drug-drug interactions involving OATP1B1 substrates continue to be reported, including several involving tyrosine kinase inhibitors (TKI).

EXPERIMENTAL DESIGN

OATP1B1-mediated activity in overexpressing HEK293 cells and hepatocytes was assessed in the presence of FDA-approved TKIs, while rosuvastatin pharmacokinetics in the presence of an OATP1B1 inhibiting TKI were measured in vivo. Tyrosine phosphorylation of OATP1B1 was determined by LC/MS-MS-based proteomics and transport function was measured following exposure to siRNAs targeting 779 different kinases.

RESULTS

Twenty-nine of 46 FDA-approved TKIs studied significantly inhibit OATP1B1 function. Inhibition of OATP1B1 by TKIs, such as nilotinib, is predominantly noncompetitive, can increase systemic concentrations of rosuvastatin in vivo, and is associated with reduced phosphorylation of OATP1B1 at tyrosine residue 645. Using genetic screens and functional validation studies, the Src kinase LYN was identified as a potential regulator of OATP1B1 activity that is highly sensitive to inhibition by various TKIs at clinically relevant concentrations.

CONCLUSIONS

A novel kinase-dependent posttranslational mechanism of OATP1B1 activation was identified and interference with this process by TKIs can influence the elimination of a broad range of xenobiotic substrates.

Neuronal uptake transporters contribute to oxaliplatin neurotoxicity in mice

Peripheral neurotoxicity is a debilitating condition that afflicts up to 90% of patients with colorectal cancer receiving oxaliplatin-containing therapy. Although emerging evidence has highlighted the importance of various solute carriers to the toxicity of anticancer drugs, the contribution of these proteins to oxaliplatin-induced peripheral neurotoxicity remains controversial. Among candidate transporters investigated in genetically engineered mouse models, we provide evidence for a critical role of the organic cation transporter 2 (OCT2) in satellite glial cells in oxaliplatin-induced neurotoxicity, and demonstrate that targeting OCT2 using genetic and pharmacological approaches ameliorates acute and chronic forms of neurotoxicity. The relevance of this transport system was verified in transporter-deficient rats as a secondary model organism, and translational significance of preventive strategies was demonstrated in preclinical models of colorectal cancer. These studies suggest that pharmacological targeting of OCT2 could be exploited to afford neuroprotection in cancer patients requiring treatment with oxaliplatin.

TP-0903 is active in models of drug-resistant acute myeloid leukemia

Effective treatment for AML is challenging due to the presence of clonal heterogeneity and the evolution of polyclonal drug resistance. Here, we report that TP-0903 has potent activity against protein kinases related to STAT, AKT, and ERK signaling, as well as cell cycle regulators in biochemical and cellular assays. In vitro and in vivo, TP-0903 was active in multiple models of drug-resistant FLT3 mutant AML, including those involving the F691L gatekeeper mutation and bone marrow microenvironment–mediated factors. Furthermore, TP-0903 demonstrated preclinical activity in AML models with FLT3-ITD and common co-occurring mutations in IDH2 and NRAS genes. We also showed that TP-0903 had ex vivo activity in primary AML cells with recurrent mutations including MLL-PTD, ASXL1, SRSF2, and WT1, which are associated with poor prognosis or promote clinical resistance to AML-directed therapies. Our preclinical studies demonstrate that TP-0903 is a multikinase inhibitor with potent activity against multiple drug-resistant models of AML that will have an immediate clinical impact in a heterogeneous disease like AML.

TP-0903, a multikinase inhibitor, demonstrates preclinical activity in models of drug-resistant AML, including those involving FLT3 mutations, bone marrow microenvironment-mediated factors and recurrent mutations.

Targeting drug transporters to prevent chemotherapy-induced peripheral neuropathy

Chemotherapy-induced peripheral neuropathy is a debilitating toxicity that adversely affects patient quality and course of treatment. Recent findings have demonstrated that the etiology of peripheral neuropathy is dependent on transporter-mediated accumulation in dorsal root ganglia, and targeting this mechanism can afford neurological protection without compromising therapeutic efficacy.

Role of SLC transporters in toxicity induced by anticancer drugs

INTRODUCTION

. Membrane transporters are integral to the maintenance of cellular integrity of all tissue and cell types. While transporters play an established role in the systemic pharmacokinetics of therapeutic drugs, tissue specific expression of uptake transporters can serve as an initiating mechanism that governs the accumulation and impact of cytotoxic drugs.

AREAS COVERED

. This review provides an overview of organic cation transporters as determinants of chemotherapy-induced toxicities. We also provide insights into the recently updated FDA guidelines for in vitro drug interaction studies, with a particular focus on the class of tyrosine kinase inhibitors as perpetrators of transporter-mediated drug interactions.

EXPERT OPINION

. Studies performed over the last few decades have highlighted the important role of basolateral uptake and apical efflux transporters in the pathophysiology of drug-induced organ damage. Increased understanding of the mechanisms that govern the accumulation of cytotoxic drugs has provided insights into the development of novel strategies to prevent debilitating toxicities. Furthermore, we argue that current regulatory guidelines provide inadequate recommendations for in vitro studies to identify substrates or inhibitors of drug transporters. Therefore, the translational and predictive power of FDA-approved drugs as modulators of transport function remains ambiguous and warrants further revision of the current guidelines.

Solute Carrier Transportome in Chemotherapy-Induced Adverse Drug Reactions

Members of the solute carrier (SLC) family of transporters are responsible for the cellular influx of a broad range of endogenous compounds and xenobiotics. These proteins are highly expressed in the gastrointestinal tract and eliminating organs such as the liver and kidney, and are considered to be of particular importance in governing drug absorption and elimination. Many of the same transporters are also expressed in a wide variety of organs targeted by clinically important anticancer drugs, directly affect cellular sensitivity to these agents, and indirectly influence treatment-related side effects. Furthermore, targeted intervention strategies involving the use of transport inhibitors have been recently developed, and have provided promising lead candidates for combinatorial therapies associated with decreased toxicity. Gaining a better understanding of the complex interplay between transporter-mediated on-target and off-target drug disposition will help guide the further development of these novel treatment strategies to prevent drug accumulation in toxicity-associated organs, and improve the safety of currently available treatment modalities. In this report, we provide an update on this rapidly emerging field with particular emphasis on anticancer drugs belonging to the classes of taxanes, platinum derivatives, nucleoside analogs, and anthracyclines.

Development and validation of a UPLC-MS/MS analytical method for dofetilide in mouse plasma and urine, and its application to pharmacokinetic study

A novel method using UPLC with tandem mass-spectrometric detection (UPLC-MS/MS) with positive electrospray ionization was developed for the detection of the antiarrhythmic drug, dofetilide, in mouse plasma and urine. Protein precipitation was performed on 10 μL of plasma and 2 μL of urine samples using dofetilide-D4 as an internal standard, and separation of the analyte was accomplished on a C18 analytical column with the flow of 0.40 mL/min. Subsequently, the method was successfully applied to determine the pharmacokinetic parameters of dofetilide following oral and intravenous administration. The calibration curve was linear over the selected concentration range (R² ≥ 0.99), with a lower limit of quantitation of 5 ng/mL. The intra-day and inter-day precisions, and accuracies obtained from a 5-day validation ranged from 3.00 to 7.10%, 3.80-7.20%, and 93.0-106% for plasma, and 3.50-9.00%, 3.70-10.0%, 87.0-106% for urine, while the recovery of dofetilide was 93.7% and 97.4% in plasma and urine, respectively. The observed pharmacokinetic profiles revealed that absorption is the rate-limiting step in dofetilide distribution and elimination. Pharmacokinetic studies illustrate that the absolute bioavailability of dofetilide in the FVB strain mice is 34.5%. The current developed method allows for accurate and precise quantification of dofetilide in micro-volumes of plasma and urine, and was found to be suitable for supporting in vivo pharmacokinetic studies.

Recent Developments of Novel Pharmacologic Therapeutics for Prevention of Chemotherapy-Induced Peripheral Neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is a common and dose-limiting toxicity, negatively affecting both quality of life and disease outcomes. To date, there is no proven preventative strategy for CIPN. Although multiple randomized trials have evaluated a variety of pharmacologic interventions for the treatment of CIPN, only duloxetine has shown clear efficacy in a phase III study. The National Cancer Institute's Symptom Management and Health-Related Quality of Life Steering Committee has identified CIPN as a priority for translational research in cancer care. Promising advances in preclinical research have identified several novel preventative and therapeutic targets, which have the potential to transform the care of patients with this debilitating neurotoxicity. Here, we provide an overarching view of emerging strategies and therapeutic targets that are currently being evaluated in CIPN.

Carvedilol inhibits EGF-mediated JB6 P+ colony formation through a mechanism independent of adrenoceptors

Carvedilol is reported to prevent cancers in humans and animal models. However, a molecular mechanism has yet to be established, and the extent to which other β-blockers are chemopreventive remains relatively unknown. A comparative pharmacological approach was utilized with the expectation that a mechanism of action could be devised. JB6 Cl 41-5a (JB6 P+) murine epidermal cells were used to elucidate the chemopreventative properties of β-blockers, as JB6 P+ cells recapitulate in vivo tumor promotion and chemoprevention. The initial hypothesis was that β-blockers that are GRK/β-arrestin biased agonists, like carvedilol, are chemopreventive. Sixteen β-blockers of different classes, isoproterenol, and HEAT HCl were individually co-administered with epidermal growth factor (EGF) to JB6 P+ cells to examine the chemopreventative properties of each ligand. Cytotoxicity was examined to ensure that the anti-transformation effects of each ligand were not due to cellular growth inhibition. Many of the examined β-blockers suppressed EGF-induced JB6 P+ cell transformation in a non-cytotoxic and concentration-dependent manner. However, the IC₅₀ values are high for the most potent inhibitors (243, 326, and 431 nM for carvedilol, labetalol, and alprenolol, respectively) and there is no correlation between pharmacological properties and inhibition of transformation. Therefore, the role of α1- and β2-adrenergic receptors (AR) was examined by standard competition assays and shRNA targeting β2-ARs, the only β-AR expressed in JB6 P+ cells. The results reveal that pharmacological inhibition of α1- and β2-ARs and genetic knockdown of β2-ARs did not abrogate carvedilol-mediated inhibition of EGF-induced JB6 P+ cell transformation. Furthermore, topical administration of carvedilol protected mice from UV-induced skin damage, while genetic ablation of β2-ARs increased carvedilol-mediated effects. Therefore, the prevailing hypothesis that the chemopreventive property of carvedilol is mediated through β-ARs is not supported by this data.

Drug transporters and anthracycline-induced cardiotoxicity

The solute carrier superfamily comprises of uptake transporters that can contribute to the absorption and elimination of a broad array of clinically important drugs. Recent studies have suggested that the tissue-specific expression of these transporters may have important consequences for an individual's susceptibility to drug-induced organ damage or to drug–drug interactions. Polymorphic variants have been identified in genes encoded by this family, and some of these have been associated with functional changes in transport function and response to anthracycline-induced toxicity and efficacy. Here, we review recent advances in the role solute carrier transporters play in anthracycline-induced cardiotoxicity, highlight potential implications of genetic variants that may contribute to drug response and discuss novel technologies to study mechanisms of anthracycline transport.

Phosphoproteome profiling provides insight into the mechanism of action for carvedilol-mediated cancer prevention

Recent studies suggest that the β-blocker drug carvedilol prevents skin carcinogenesis but the mechanism is unknown. Carvedilol is one of a few β-blockers identified as biased agonist based on an ability to promote β-arrestin-mediated processes such as ERK phosphorylation. To understand the role of phosphoproteomic signaling in carvedilol's anticancer activity, the mouse epidermal JB6 P+ cells treated with EGF, carvedilol, or their combination were analyzed using the Phospho Explorer Antibody Array containing 1318 site-specific and phospho-specific antibodies of over 30 signaling pathways. The array data indicated that both EGF and carvedilol increased phosphorylation of ERK's cytosolic target P70S6 K while its nuclear target ELK-1 were activated only by EGF; Furthermore, EGF-induced phosphorylation of ELK-1 and c-Jun was attenuated by carvedilol. Subcellular fractionation analysis indicated that ERK nuclear translocation induced by EGF was blocked by co-treatment with carvedilol. Western blot and luciferase reporter assays confirmed that the biased β-blockers carvedilol and alprenolol blocked EGF-induced phosphorylation and activation of c-Jun/AP-1 and ELK-1. Consistently, both carvedilol and alprenolol strongly prevented EGF-induced neoplastic transformation of JB6 P+ cells. Remarkably, oral carvedilol treatment significantly inhibited the growth of A375 melanoma xenograft in SCID mice. As nuclear translocation of ERK is a key step in carcinogenesis, inhibition of this event is proposed as a novel anticancer mechanism for biased β-blockers such as carvedilol.

Effects of bioactive constituents in the Traditional Chinese Medicinal formula Si-Wu-Tang on Nrf2 signaling and neoplastic cellular transformation

BACKGROUND

The nuclear factor erythroid 2-related factor 2 (Nrf2) is a potential molecular target for cancer chemoprevention. Si-Wu-Tang (SWT), a popular traditional Chinese medicine for women's health, was reported with a novel activity of cancer prevention.

PURPOSE

The present study was aimed to identify the bioactive constituents in SWT responsible for the Nrf2 activating and cancer preventive activity and explore the pharmacological mechanisms.

METHODS

Nine compounds detectable from various batches of SWT were ranked using in silico molecular docking based on their ability to interfere the forming of Nrf2-Keap1 complex. The predicted Nrf2 activating effect was validated using the antioxidant response element (ARE) luciferase reporter assay and quantitative RT-PCR analysis for select Nrf2 regulated genes Hmox1, Nqo1 and Slc7a11. The antimutagenic activity of the compounds were determined by the Ames test. The chemopreventive activity of these compounds were assessed on EGF-induced neoplastic transformation of JB6 P+ cells, an established non-cancerous murine epidermal model for studying tumor promotion and identifying cancer preventive agents. These compounds were further characterized using luciferase reporter assay on EGF-induced activation of AP-1, a known transcription factor mediating carcinogenesis.

RESULTS

Three of the nine compounds predicted as Nrf2 activators by molecular docking, gallic acid (GA), Z-liguistilide (LIG), and senkyunolide A (SA), were confirmed with highest potency of increasing the Nrf2/ARE promoter activity and upregulating the expression of Hmox1, Nqo1 and Slc7a11. In addition, GA, LIG and SA exhibited an antimutagenic activity against the direct mutagen 2-nitrofluorene while no mutagenic effects were observed at the same time in Ames test. At nontoxic concentrations, GA, LIG, and SA inhibited EGF-induced neoplastic transformation of JB6 P+ cells. Combined treatment of GA, LIG and SA, in the same ratio as detected in SWT, showed enhanced effect against JB6 transformation compared with that of the single compound alone. GA, LIG and SA, alone or in combination, suppressed EGF-induced activation of AP-1.

CONCLUSION

We identified three bioactive constituents in SWT responsible for the Nrf2 activating and cancer preventive activity. This study provides evidence supporting novel molecular basis of SWT in cancer prevention.

OATP1B2 deficiency protects against paclitaxel-induced neurotoxicity

Paclitaxel is among the most widely used anticancer drugs and is known to cause a dose-limiting peripheral neurotoxicity, the initiating mechanisms of which remain unknown. Here, we identified the murine solute carrier organic anion-transporting polypeptide B2 (OATP1B2) as a mediator of paclitaxel-induced neurotoxicity. Additionally, using established tests to assess acute and chronic paclitaxel-induced neurotoxicity, we found that genetic or pharmacologic knockout of OATP1B2 protected mice from mechanically induced allodynia, thermal hyperalgesia, and changes in digital maximal action potential amplitudes. The function of this transport system was inhibited by the tyrosine kinase inhibitor nilotinib through a noncompetitive mechanism, without compromising the anticancer properties of paclitaxel. Collectively, our findings reveal a pathway that explains the fundamental basis of paclitaxel-induced neurotoxicity, with potential implications for its therapeutic management.

Murine Pharmacokinetic Studies

Murine pharmacokinetics (PK) represents the absorption, distribution, metabolism, and elimination of drugs from the body, which helps to guide clinical studies, ultimately resulting in more effective drug treatment. The purpose of this protocol is to describe a serial bleeding protocol, obtaining blood samples at six time points from single mouse to yield a complete PK profile. This protocol has proved to be rapid, highly repeatable, and relatively easy to acquire. Comparing with the conventional PK studies, this method not only dramatically reduces animal usage, but also decreases sample variation obtained from different animals.

Topically Applied Carvedilol Attenuates Solar Ultraviolet Radiation Induced Skin Carcinogenesis

In previous studies, the β-blocker carvedilol inhibited EGF-induced epidermal cell transformation and chemical carcinogen-induced mouse skin hyperplasia. As exposure to ultraviolet (UV) radiation leads to skin cancer, the present study examined whether carvedilol can prevent UV-induced carcinogenesis. Carvedilol absorbs UV like a sunscreen; thus, to separate pharmacological from sunscreen effects, 4-hydroxycarbazole (4-OHC), which absorbs UV to the same degree as carvedilol, served as control. JB6 P⁺ cells, an established epidermal model for studying tumor promotion, were used for evaluating the effect of carvedilol on UV-induced neoplastic transformation. Both carvedilol and 4-OHC (1 μmol/L) blocked transformation induced by chronic UV (15 mJ/cm²) exposure for 8 weeks. However, EGF-mediated transformation was inhibited by only carvedilol but not by 4-OHC. Carvedilol (1 and 5 μmol/L), but not 4-OHC, attenuated UV-induced AP-1 and NF-κB luciferase reporter activity, suggesting a potential anti-inflammatory activity. In a single-dose UV (200 mJ/cm²)-induced skin inflammation mouse model, carvedilol (10 μmol/L), applied topically after UV exposure, reduced skin hyperplasia and the levels of cyclobutane pyrimidine dimers, IL1β, IL6, and COX-2 in skin. In SKH-1 mice exposed to gradually increasing levels of UV (50-150 mJ/cm²) three times a week for 25 weeks, topical administration of carvedilol (10 μmol/L) after UV exposure increased tumor latency compared with control (week 18 vs. 15), decreased incidence and multiplicity of squamous cell carcinomas, while 4-OHC had no effect. These data suggest that carvedilol has a novel chemopreventive activity and topical carvedilol following UV exposure may be repurposed for preventing skin inflammation and cancer. Cancer Prev Res; 10(10); 598-606. ©2017 AACR.

MR imaging of displaced meniscal tears of the knee: Importance of a “disproportional posterior horn sign”

Purpose: Meniscal tears associated with displaced fragments are clinically significant. We propose the "disproportional posterior horn sign" as a supportive criterion to identify a posterocentrally displaced meniscal fragment on MR imaging studies. If the meniscal posterior horn in the central portion appears larger than that in the peripheral section, it is considered positive for "disproportional posterior horn sign".

Material and Methods: MR images obtained in 42 patients with 43 lesions, confirmed to have displaced meniscal tears, were included in this study. The MR images were retrospectively evaluated for the presence of the "disproportional posterior horn sign", as well as the other known signs.

Results: The "disproportional posterior horn sign" was seen in 9 (20.9%) of 43 lesions, including 1 lateral discoid meniscal tear, 5 lateral meniscal tears and 3 medial meniscal tears. Five of them also had other signs of a displaced meniscal fragment. However, the remaining 4 cases only exhibited the "disproportional posterior horn sign". For the other MR signs, the "absent bow tie sign" was detected in 40 (93%) of 43 lesions, the "flipped meniscus sign" in 27 (62.8%) of 43 lesions, the "double posterior cruciate ligament sign" in 17 (39.5%) of 43 lesions and the "notch fragment sign" in 22 (51.2%) of 43 lesions.

Conclusion: The "disproportional posterior horn sign" is helpful in demonstrating a posterocentrally displaced meniscal fragment, especially when other characteristic signs are unremarkable or absent.

Abstract 2617: Protective effect of the β-blocker carvedilol on UVB-induced skin damage

The response to ultraviolet (UV) radiation is the primary etiologic factor leading to carcinogenesis of the skin. The effects of UV radiation on the skin is generally transient, but the long term consequences can be carcinogenic. Despite growing public awareness and the use of sunscreen to prevent skin cancer, the incidence continues to rise, and therefore there is a need to develop innovative chemoprevention strategies. Previously, we showed that the receptor subtype nonselective β-adrenergic receptor antagonist (i.e., β-blocker) carvedilol prevented EGF and UVB-mediated neoplastic transformation of the mouse epidermal cell line JB6 P+, indicating its chemopreventive potential against skin cancer. To demonstrate the in vivo effects of carvedilol, in the present study, hairless SKH-1 mice were irradiated for two weeks with 200 mJ/cm2 of UVB and drugs were topically applied immediately after the radiation. Since carvedilol is able to absorb UV, its analogue 4-hydroxycarbazole, which has the same UVB absorption profiling as carvedilol but does not function as a β-blocker, was included as a sunscreen control. Significant skin thickening measured by bi-fold skin thickness on the dorsal skin was observable within a week and over the course of the two-week period. Treatment with carvedilol, but not the analogue, reduced UVB-induced skin hyperplasia, reddening and inflammation. Furthermore, carvedilol, but not the analogue, reduced H2O2 and UVB- induced cytotoxicity and reactive oxygen species production in JB6 P+ cells. To elucidate the molecular mechanism(s) for carvedilol's chemopreventive activity, the signaling profile for JB6 P+ cells treated with EGF and/or carvedilol for 15 min was examined using a Phospho Explorer Antibody Microarray containing 1318 site and phosphor-specific antibodies from over 30 signaling pathways. The antibody array data suggested that the phosphorylation of the intracellular signaling pathways involved in skin carcinogenesis, AP-1 and NF-kB, were increased by EGF but attenuated by carvedilol. These results were validated using luciferase reporter assays. The array data also suggested that carvedilol was able to induce the expression of tumor suppressors p53 and PTEN. In addition, the checkpoint kinases CHK1 and CHK2 and other cell-cycle regulators such as cyclins were also upregulated by carvedilol, suggesting a role in carvedilol's protective effect. Since highly abundant mutations are observable in sun-exposed skin, our current work is to examine the effects of carvedilol on the production of cyclo-pyrimidine dimers (CPDs) induced by UVB. In conclusion, our study has demonstrated novel mechanisms underlying carvedilol's chemopreventive activity against skin cancer. Since carvedilol and other β-blockers are FDA approved drugs and relatively safe, they may offer a new approach of prevention for UVB-induced skin cancer.

Citation Format: Kevin M. Huang, Kristan H. Cleveland, Steven Yeung, Bradley T. Andresen, Ying Huang. Protective effect of the β-blocker carvedilol on UVB-induced skin damage. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2617.

Abstract 1915: Effects of carvedilol, a β-adrenergic receptor antagonist, on UVB-induced skin cancer development and its possible mechanism of action

Recently, we proposed that carvedilol, a β-adrenergic receptor antagonist (i.e., β-blocker), can act as a chemopreventive agent against skin cancer (Chang et al., Cancer Prev. Res, 2014). Since approximately 90 percent of diagnosed non-melanoma skin cancers are associated with exposure to ultraviolet (UV) radiation from the sun, the primary form being UVB irradition, we hypothesized that carvedilol will prevent UVB-induced skin carcinogenesis. The transformable JB6 P+ cell line, an established model for studying skin cancer promotion, was used for evaluating the impact of carvedilol on UVB-induced oxidative damage. Exposures of JB6 P+ cells to 50 - 400 mJ/cm2 UVB resulted in a dose-dependent decrease in cell viability. 25 mJ/cm2 UVB induced ∼20% of cell death, and thus was chosen to study the effect of carvedilol. 0.1 to 1.0 μM carvedilol prevented UVB-induced growth inhibition and apoptosis; however, 3 to 5 μM carvedilol, although nontoxic alone, enhanced UVB-induced cell death. Contrarily, all concentrations of carvedilol tested blocked H2O2-dependent cytotoxicity of JB6 P+ cells. Thus, although both UVB and H2O2 are classic inducers of oxidative stress resulting in DNA damage and tumor promotion, carvedilol may modulate UVB and H2O2-mediated effects via different mechanisms. Cell signaling studies revealed that carvedilol inhibited EGF-induced phosphorylation of AKT at S473 and GSK3β at S9 as well as AP-1 transactivation, which are all well-known principal mediators of skin carcinogenesis. A pitfall with experiments involving UV exposure is the potential UV absorption properties of test compounds. Examination of the structure of carvedilol indicates that it will absorb UV due to the presence of a carbazole moiety and benzene rings. If not controlled in the experiments, the observed effects will be a mixture of pharmacological properties and a UV absorption effect. To identify a solution for this problem, 4-hydroxycarbazole, which mimicks the carbazole moiety of carvedilol, was found to have the same UVB absorption properties as carvedilol but does not function as a β-adrenergic receptor antagonist nor inhibit EGF-mediated colony formation of JB6 P+ cells. 4-hydroxycarbazole is currently being used to repeat the UVB experiments mentioned above to act as a sunscreen/absorption control. Additionally, 4-hydroxycarbazole should be used as a control for carvedilol for other on-going studies for prevention of UVB-induced skin cancer. Since 4-hydroxycarbazole only has the UV absorption (i.e., sunscreen) effect, we anticipate that it will have some protective effect, but that carvedilol provides greater preventive activity against UVB-induced skin carcinogenesis. Since carvedilol and other β-blockers are already FDA-approved drugs, these results may be readily translated into clinical trials as a new approach for skin cancer chemoprevention.

Citation Format: Kevin M. Huang, Andy Chang, Kristan H. Cleveland, Bradley T. Andresen, Ying Huang. Effects of carvedilol, a β-adrenergic receptor antagonist, on UVB-induced skin cancer development and its possible mechanism of action. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1915. doi:10.1158/1538-7445.AM2015-1915

Prevention of skin carcinogenesis by the β-blocker carvedilol

The stress-related catecholamine hormones and the α- and β-adrenergic receptors (α- and β-AR) may affect carcinogenesis. The β-AR GRK/β-arrestin biased agonist carvedilol can induce β-AR-mediated transactivation of the EGFR. The initial purpose of this study was to determine whether carvedilol, through activation of EGFR, can promote cancer. Carvedilol failed to promote anchorage-independent growth of JB6 P(+) cells, a skin cell model used to study tumor promotion. However, at nontoxic concentrations, carvedilol dose dependently inhibited EGF-induced malignant transformation of JB6 P(+) cells, suggesting that carvedilol has chemopreventive activity against skin cancer. Such effect was not observed for the β-AR agonist isoproterenol and the β-AR antagonist atenolol. Gene expression, receptor binding, and functional studies indicate that JB6 P(+) cells only express β2-ARs. Carvedilol, but not atenolol, inhibited EGF-mediated activator protein-1 (AP-1) activation. A topical 7,12-dimethylbenz(α)anthracene (DMBA)-induced skin hyperplasia model in SENCAR mice was utilized to determine the in vivo cancer preventative activity of carvedilol. Both topical and oral carvedilol treatment inhibited DMBA-induced epidermal hyperplasia (P < 0.05) and reduced H-ras mutations; topical treatment being the most potent. However, in models of established cancer, carvedilol had modest to no inhibitory effect on tumor growth of human lung cancer A549 cells in vitro and in vivo. In conclusion, these results suggest that the cardiovascular drug carvedilol may be repurposed for skin cancer chemoprevention, but may not be an effective treatment of established tumors. More broadly, this study suggests that β-ARs may serve as a novel target for cancer prevention.

Unusual manifestations of vertebral osteomyelitis: intraosseous lesions mimicking metastases

BACKGROUND AND PURPOSE

Vertebral osteomyelitis can have different imaging manifestations. The purpose of this study was to demonstrate the unusual MR imaging patterns of vertebral osteomyelitis with intraosseous lesions mimicking metastases.

MATERIALS AND METHODS

From September 2000 to August 2007, 7 patients were selected from our data base of 214 patients with confirmed vertebral osteomyelitis and MR images. All of those having misinterpreted MR imaging reports and unusual imaging patterns were analyzed. The presence of a peripheral curvilinear area of low signal intensity in an osseous lesion (the rim sign) and a peripheral rim of high signal intensity on T2-weighted images around an osseous lesion (the halo sign) was evaluated. Follow-up MR imaging studies were performed in all patients.

RESULTS

The patients were 5 men and 2 women, with an age range of 42-80 years. MR imaging findings of those with vertebral osteomyelitis showed a solitary lesion in 2 and multiple lesions in 5 patients. The intraosseous lesions revealed low signal intensity on T1-weighted images, mixed or high signal intensity on T2-weighted images, high signal intensity on short tau inversion recovery images, and global or marginal enhancement. The rim sign was found in 6 (86%) patients; halo sign, in 7 (100%); preserved intervertebral disks, in 7 (100%); and limited paraspinal or epidural inflammation, in 6 (86%). Images of all patients demonstrated healing or almost healed changes on the follow-up MR imaging studies.

CONCLUSION

Vertebral osteomyelitis can have MR imaging patterns mimicking osseous metastases. Recognition of these unusual imaging manifestations, together with clinical and histopathologic analysis, may aid in reaching the correct diagnosis.

Endovascular treatment of brain-stem arteriovenous malformations: safety and efficacy

Our purpose was to evaluate the safety and efficacy of endovascular treatment of brain-stem arteriovenous malformations (AVMs), reviewing six cases managed in the last 5 years. There were four patients who presented with bleeding, one with a progressive neurological deficit and one with obstructive hydrocephalus. Of the six patients, one showed 100%, one 90%, two 75% and two about 50% angiographic obliteration of the AVM after embolisation; the volume decreased about 75% on average. Five patients had a good outcome and one an acceptable outcome, with a mild postprocedure neurological deficit; none had further bleeding during midterm follow-up. Endovascular management of a brain-stem AVM may be an alternative to treatment such as radiosurgery and microsurgery in selected cases. It may be not as risky as previously thought. Embolisation can reduce the size of the AVM and possibly make it more treatable by radiosurgery and decrease the possibility of radiation injury.

Diabetic ketoacidosis and hypogonadotropic hypogonadism in association with transfusional hemochromatosis in a man with beta-thalassemia major

We report a 23-year-old man with beta-thalassemia major and transfusional hemochromatosis, which manifested as diabetic ketoacidosis and hypogonadotropic hypogonadism. This unusual presentation of diabetic ketoacidosis in hemochromatosis has rarely been reported. Magnetic resonance imaging of the abdomen showed decreased signal intensity in the liver, spleen, and pancreas. In addition, the pituitary gland also showed heterogeneous low signal intensity, compatible with hemochromatosis. He was treated with insulin supplements and pulsatile human chorionic gonadotropin administration. Clinical improvement was noted after hormone replacement. Intensive iron chelation therapy was given to prevent cardiac complications, and to restore his gonadal function. During follow-up, the patient experienced improvement in libido and sexual potency.

Bilateral anomalous origins of the posterior meningeal artery from the ascending pharyngeal arteries

We present a rare case of angiographically confirmed dural arteriovenous fistula supplied mainly by the posterior meningeal artery with bilateral anomalous origins from the bilateral ascending pharyngeal arteries. The bilaterality of the origins of the posterior meningeal artery is important in the angiographic diagnosis and management of a dural vascular malformation in the posterior fossa or the posterior part of the falx cerebri.

Tissue segmentation-assisted analysis of fMRI for human motor response: an approach combining artificial neural network and fuzzy C means

The authors have developed an automated algorithm for segmentation of magnetic resonance images (MRI) of the human brain. They investigated the quantitative analysis of tissue-specific human motor response through an approach combining gradient echo functional MRI and automated segmentation analysis. Fifteen healthy volunteers, placed in a 1.5 T clinical MR imager, performed a self-paced finger opposition throughout the activation periods. T1-weighted images (WI), T2WI, and proton density WI were acquired for segmentation analysis. Single-slice axial T2* fast low-angle shot (FLASH) images were obtained during the functional study. Pixelwise cross-correlation analysis was performed to obtain an activation map. A cascaded algorithm, combining Kohonen feature maps and fuzzy C means, was applied for segmentation. After processing, masks for gray matter, white matter, small vessels, and large vessels were generated. Tissue-specific analysis showed a signal change rate of 4.53% in gray matter, 2.98% in white matter, 5.79% in small vessels, and 7.24% in large vessels. Different temporal patterns as well as different levels of activation were identified in the functional response from various types of tissue. High correlation exists between cortical gray matter and subcortical white matter (r = 0.957), while the vessel behaves somewhat different temporally. The cortical gray matter fits best to the assumed input function (r = 0.957) followed by subcortical white matter (r = 0.829) and vessels (r = 0.726). The automated algorithm of tissue-specific analysis thus can assist functional MRI studies with different modalities of response in different brain regions.

Imaging in the diagnosis and follow-up evaluation of vertebral artery dissection

The purpose of this report is to discuss the value of ultrasonographic examination in the diagnosis and follow-up evaluation of vertebral artery dissection. We collected data on 8 patients with 11 pathologic vessels: 9 were affected intracranially and 6 were affected extracranially. Four vessels were affected in both intracranial and extracranial segments. Extracranial color-flow duplex sonography could detect abnormalities in every extracranial vertebral artery dissection. Most abnormal findings were non-specific, including severely reduced flow, absence of flow, and absence of diastolic flow. A specific finding (intramural hematoma) was noted in one artery. Abnormal transcranial color-coded sonographic findings included absence of flow, reduced velocity and reversed flow direction. Three intracranial dissecting arteries showed normal findings on transcranial color-coded sonography. Ultrasonographic follow-up study revealed evidence of improvement; this was noted almost exclusively in the extracranial segments of the vertebral artery but infrequently in the intracranial segment. Extracranial color-flow duplex sonography is sensitive in the detection of extracranial vertebral artery dissection, both in initial diagnosis and in follow-up evaluation.

Factors affecting the outcome of surgical treatment of acromegaly

PURPOSE

To assess the results of and factors associated with the outcome of surgery for acromegaly.

METHODS

We retrospectively examined the medical records of acromegalic patients who underwent trans-sphenoidal adenomectomy at our hospital during the period of January 1991 through August 1997. Preoperative evaluations included measurement of basal serum growth hormone (GH), insulin-like growth factor-I (IGF-I), prolactin (PRL), GH response to oral glucose, and GH and PRL response to bromocriptine, as well as pituitary magnetic resonance (MR) imaging. Postoperative evaluations included measurement of basal serum GH and IGF-I concentrations, and pituitary MR imaging.

RESULTS

Thirty patients (14 men) with a mean age of 38 years were included. The mean follow-up period was 50 months (range, 15-90 mo). Ten of the 30 patients (33%) had early postoperative (1 mo after surgery) GH levels of less than 5 ng/mL. Twenty patients (67%) had final postoperative (last follow-up, 15-90 mo after surgery) GH levels of less than 5 ng/mL. Preoperative GH levels were positively correlated with early postoperative GH levels (r = 0.458, p = 0.011) and final postoperative GH levels (r = 0.479, p = 0.007). Early postoperative GH levels were also positively correlated with final postoperative GH levels (r = 0.595, p = 0.001). Tumor grade and stage were not significantly correlated with early or final postoperative GH levels. Thirteen of 21 patients (62%) who had postoperative MR imaging follow-up had residual tumor. There was no surgical mortality.

CONCLUSIONS

These results highlight that acromegaly is not easily treated with surgery alone. The preoperative GH level was associated with the surgical outcome.

Impact of magnetic resonance imaging on the advancement of medicine

Magnetic resonance (MR) imaging has had a significant impact in many areas of modern medicine. Because of its good image resolution, tissue characterization, and functional assessment of various organs and systems, MR imaging has become an important modern technology in clinical practice and medical research. MR imaging has great flexibility in viewing anatomic structures in arbitrary imaging planes. With ultrafast MR imaging techniques, images of areas of interest can be obtained in a very short time, with elimination of physiologic motion artifacts. MR angiography obviates the need for catheterization and provides highly detailed images of the vascular anatomy, even of structures as small as the coronary artery. MR cholangiopancreatography provides results comparable to those of endoscopic retrograde cholangiopancreatography in many hepatobiliary diseases. Functional MR imaging is a new tool to evaluate physiologic function. MR spectroscopy has been used to explore the metabolic activity of normal and diseased organs and structures. The applications of MR imaging in clinical medicine and biomedical research are expanding.

Application of Fluid-Attenuated Inversion Recovery pulse sequence in children with tuberous sclerosis

To evaluate the application of Fluid-Attenuated Inversion Recovery (FLAIR) pulse sequence to increase the sensitivity of detecting tubers in tuberous sclerosis patients compared with fast spin-echo T2-weighted (FSET2W) image, we obtained 12 magnetic resonance (MR) images in 10 patients (mean age = 57.7 months old). Among the 12 examinations, 114 cortical and 128 subcortical tubers were revealed on the FLAIR images, whereas 54 and 72 tubers were found respectively on the FSET2W images. This may be due to the FLAIR pulse sequences remarkably attenuated CSF signals in comparison with the FSET2W images. However, FSET2W image delineated more subependymal nodules than FLAIR imaging did. Gd-DTPA enhanced T1W image is the most suitable pulse sequence to detect giant cell astrocytoma near the foramen of Monro. The results in cases of infants and little children were similar.

Clathrin functions in the absence of heterotetrameric adaptors and AP180-related proteins in yeast

The major coat proteins of clathrin-coated vesicles are the clathrin triskelion and heterotetrameric associated protein (AP) complexes. The APs are thought to be involved in cargo capture and recruitment of clathrin to the membrane during endocytosis and sorting in the trans-Golgi network/endosomal system. AP180 is an abundant coat protein in brain clathrin-coated vesicles, and it has potent clathrin assembly activity. In Saccharomyces cerevisiae, there are 13 genes encoding homologs of heterotetrameric AP subunits and two genes encoding AP180-related proteins. To test the model that clathrin function is dependent on the heterotetrameric APs and/or AP180 homologs, yeast strains containing multiple disruptions in AP subunit genes, as well as in the two YAP180 genes, were constructed. Surprisingly, the AP deletion strains did not display the phenotypes associated with clathrin deficiency, including slowed growth and endocytosis, defective late Golgi protein retention and impaired cytosol to vacuole/autophagy function. Clathrin-coated vesicles isolated from multiple AP deletion mutants were morphologically indistinguishable from those from wild-type cells. These results indicate that clathrin function and recruitment onto membranes are not dependent upon heterotetrameric adaptors or AP180 homologs in yeast. Therefore, alternative mechanisms for clathrin assembly and coated vesicle formation, as well as the role of AP complexes and AP180-related proteins in these processes, must be considered.

Solitary vertebral collapse: distinction between benign and malignant causes using MR patterns

Differentiation of benign from malignant causes of vertebral compression fracture can be difficult at a single location. We studied 37 patients with solitary vertebral collapse (SVC) in the spine using magnetic resonance imaging (MRI). Sixteen of them were found to have a benign cause of SVC, while the remaining 21 were found to have malignancy. The following four MRI characteristics were investigated: ill- or well-defined margin of the intravertebral lesion (P < 0.005); pedicle involvement (P < 0.05); MR enhancement pattern (P < 0.005); and paravertebral soft tissue lesion (PSL) (P < 0.025). It was found that cases of malignant SVC tended to have an ill-defined margin, abnormal signal involvement of the pedicle, a marked and heterogenous MR enhancement pattern, and irregular nodular-type PSL. Pedicle change with expansile lesion totally excluded a benign cause. By using these criteria, we were able to differentiate benign or malignant causes of SVC accurately.

Early diagnosis of single segment vertebral osteomyelitis--MR pattern and its characteristics

Nine cases of single segment vertebral osteomyelitis were included based on the single level of vertebral body involvement according to the MR findings. They were 3 cases with tuberculous infection and 6 cases with pyogenic infection. The vertebral body involvement was presented as abnormal signal changes (100%) and heterogenous enhancement (77.7%). They usually caused the cortical disruption in its anterior aspect (100%). It goes along the upward subligamentous spread (100%) most often, then the upper disc involvement (66.6%) and downward subligamentous spread (55.5%). The lower disc involvement is least common (11.1%). By using these criteria, the single segment vertebral osteomyelitis could be earlier diagnosed.

Cerebral venous thrombosis in patients with nephrotic syndrome--case reports

The authors describe two cases of cerebral venous thrombosis (CVT) in patients with nephrotic syndrome. The main clinical features of CVT were persistent headache, hemiparesis, and seizure, and the diagnosis was based on magnetic resonance imaging and magnetic resonance angiography. Both showed acquired deficiency of free protein S. The neurologic symptoms remained stationary in the first patient, who received no anticoagulation therapy, but resolved rapidly in the second, treated with intravenous heparin and supplemented with fresh frozen plasma. CVT should be suspected in patients with nephrotic syndrome who present with symptoms of intracranial hypertension or any focal neurologic deficit.

Diaschisis in chronic viral encephalitis with Koshevnikov syndrome

The authors report a 61-year-old man with chronic viral encephalitis and Koshevnikov syndrome occurring 42 months after initial symptom of right hemiparesis. Serial computed tomography of the brain showed changes in the attenuation of the left temporal lobe lesion over time. Magnetic resonance images of the brain showed enlargement of left temporoparietooccipital lobes with cortical gyral enhancement on T1-weighted images following intravenous administration of gadolinium-DTPA. 99mTc-HMPAO single-photon emission computerized tomography showed increased radioactivity and hyperperfusion in the left temporoparietal region with paradoxically decreased local tissue perfusion at the contralateral right hemisphere. Follow-up magnetic resonance images of the brain 4 years later showed atrophy of bilateral cerebral hemispheres. We postulate that a "transcallosal diaschisis" with subsequent degeneration is a possible mechanism. A brain biopsy from the left temporal lobe lesion showed pictures compatible with viral encephalitis probably herpes simplex encephalitis.

Objective evaluation of oral and maxillofacial sensory nerves

OBJECTIVE

The purpose of this article is to recommend a set of methods for the clinical objective evaluation of neurosensory nerves and to establish criteria for the clinical objective evaluation of oral and maxillofacial regions in a Chinese population.

METHODS

Sensations in the oral and maxillofacial regions of 35 healthy subjects were objectively and quantitatively evaluated by means of two-point discrimination, static light touch, brush directional stroke, and thermal discrimination.

RESULTS

Criteria for the clinical neurosensory evaluation were established for the sensations of the oral and maxillofacial regions of healthy Chinese.

CONCLUSIONS

Two-point discrimination, static light touch, brush directional discrimination, and thermal discrimination can provide objective, quantitative information for the evaluation of sensory nerve impairment. These convenient methods represent the important tools in the diagnosis and treatment of sensory nerve impairment in oral and maxillofacial regions.

Oct-1 binds promoter elements required for transcription of the GnRH gene

The GnRH gene is exclusively expressed in a discrete population of neurons in the hypothalamus. The promoter-proximal 173 bp of the rat GnRH gene are highly conserved through evolution and are bound by multiple nuclear proteins found in the neuronal cell line, GT1-7, a model for the GnRH-expressing hypothalamic neuron. To explore the protein-DNA interactions that occur within this promoter and the role of these interactions in targeting GnRH gene expression, we have mutagenized individual binding sites in this region. Deoxyribonuclease I protection experiments reveal that footprint 2, a 51-bp sequence that confers a 20-fold induction of the GnRH gene, is comprised of at least three independent protein-binding sites. Transfections of the GnRH promoter-reporter plasmid containing a series of block mutations of footprint 2 into GT1-7 neurons indicate that each of the three putative component sites contributes to transcriptional activity. Mutations in footprint 4 also decrease GnRH gene expression. Footprint 4 and the promoter-proximal site in footprint 2 contain octamer-like motifs, an element that is also present in the neuron-specific enhancer of the rat GnRH gene located approximately 1.6 kb upstream of the promoter. Previous studies in our laboratory have demonstrated that two enhancer octamer sites are bound by the POU-homeodomain transcription factor Oct-1 in GT1-7 cells. We now show that Oct-1 binds the octamer motifs within footprints 2 and 4. Thus, Oct-1 plays a critical role in the regulation of GnRH transcription, binding functional elements in both the distal enhancer and the promoter-proximal conserved region.

Relationships of orbital computed tomographic findings and activity scores to the prognosis of corticosteroid therapy in patients with Graves' ophthalmopathy

To elucidate the relationships of orbital computed tomographic findings and activity scores to the prognosis of corticosteroid therapy in patients with Graves' ophthalmopathy, 22 cases were treated with corticosteroid. Orbital computed tomographic was performed before treatment and the maximal muscle areas of rectus muscle bellies were calculated from the coronal images. Activity scores were calculated according to the recommendations of an international ad hoc committee. The clinical severity of the eye disease was based on the NOSPECS classification. Observation of the effectiveness of treatment at 6 months allowed patients to be classified into good responders or poor responders. Twelve of 22 patients (54.5%) belonged to the good responders. The total muscle areas were less in good responders. Although the total muscle areas were significantly correlated with the activity scores, no difference in the activity scores was noted between these two groups. We concluded that although activity score seems to be a predictor of initial responsiveness to anti-inflammatory drugs, the maximal muscle area is a prognostic factor of corticosteroid therapy in patients with Graves' ophthalmopathy.

Magnetic resonance imaging in patients with hemodialysis-related arthropathy

From April 1993 to December 1993, we prospectively studied the knees of 15 patients (mean age, 48 +/- 11 yr) receiving long-term hemodialysis (mean duration, 9 +/- 4 yr) using magnetic resonance imaging (MRI) techniques including, T1 weighted spin-echo, multiplanar gradient recalled, and postcontrast T1 with chemical shift-selective, fat-saturation pulse sequences. Analysis of these images revealed that the three findings most indicative of hemodialysis-related arthropathy were intramedullary, cortical and soft tissue lesions. Knee pain was significantly correlated with the presence of soft tissue lesions. Cortical lesions were usually associated with soft tissue lesions. Inflammatory changes adjacent to soft tissue lesions were demonstrated in postcontrast studies in all patients with soft tissue lesions. Increases in water content in those lesions appeared to increase the signal intensity. Our results indicate that MRI is useful in demonstrating the extent of hemodialysis-related arthropathy involvement, especially in hemodialysis patients suffering from knee pain.

Novel functions of clathrin light chains: clathrin heavy chain trimerization is defective in light chain-deficient yeast

Clathrin is a major coat protein involved in sorting and retention of proteins at the late Golgi and in endocytosis from the cell surface. The clathrin triskelion contains three heavy chains, which provide the structural backbone of the clathrin lattice and three light chains, which are thought to regulate the formation or disassembly of clathrin coats. To better understand the function of the clathrin light chain, we characterized yeast strains carrying a disruption of the clathrin light chain gene (CLC1). Light chain-deficient cells showed phenotypes similar to those displayed by yeast that have a disruption in the clathrin heavy chain gene (CHC1). In clc1-delta cells, the steady state level of the clathrin heavy chain was reduced to 20%-25% of wild-type levels and most of the heavy chain was not trimerized. If CHC1 was overexpressed in clc1-delta cells, heavy chain trimers were detected and several clc1-delta phenotypes were partially rescued. These results indicate that the light chain is important for heavy chain trimerization and the heavy chain still has some function in the absence of the light chain. In yeast, deletion of CHC1 is lethal in strains carrying the scd1-i allele, while strains carrying the scd1-v allele can survive without the heavy chain. In previous studies we isolated several multicopy suppressors of inviability of chc1-delta scd1-i cells. Surprisingly, one of these suppressors, SCD4, is identical to CLC1. Overexpression of CLC1 in viable chc1-delta scd1-v strains rescued some but not all of the phenotypes displayed by these cells. In the absence of the heavy chain, the light chain was not found in a high molecular mass complex, but still associated with membranes. These results suggest that the light chain can function independently of the clathrin heavy chain in yeast.

Magnetic resonance imaging in symptomatic/cryptogenic partial epilepsies of infants and children

In order to identify the brain lesions of symptomatic/cryptogenic partial epilepsies (S/CPEs) in infants and children, magnetic resonance imaging (MRI) studies, thorough encephalographic (EEGic) studies, and detailed clinical and neurologic evaluations were obtained in 300 infants and children who were diagnosed to have S/CPEs with onset before the age of 13 years during the past 7 years. The overall detection rate of brain lesions by MRI was 41.7% (125/300). Congenital malformations (18 cases), vascular malformations (9 cases), neurocutaneous syndromes (13 cases), and space-taking lesions (20 cases) constitute a large percentage of SPEs in infants and children. A variety of insults such as infection, ischemia, hemorrhage, trauma and metabolic disorders can result in destructive parenchymal loss lesions including porencephaly, focal atrophy, hemiatrophy, and diffuse brain atrophy (20 cases). Major etiologic factors leading to infarction, encephalomalacia, leukomalacia, included trauma, hvpoxicischemic encephalopathy (HIE), systemic lupus erythematosus (SLE), encephalitis, vasculitis, venous thrombosis, vasculopathies, and heart problems (22 cases). Mesial temporal sclerosis (MTS) could be evidenced in around 20% (18/95) of cases with temporal lobe epilepsy (TLE), which was strongly associated with past histories of febrile seizures and encephalitis complicated by status epileptics. However, cases with porencephaly, global atrophy or delayed myelination of unilateral temporal lobe on MRI were more related to HIE. With the advent of neuroimaging techniques, particularly MRI, a wide variety of underlying pathology can be detected as a cause of symptomatic partial epilepsies in pediatric patients. The occurrence of S/CPE indicates the presence of localized brain dysfunction, and many of the causes are potentially treatable. An orderly and thorough clinical and laboratory investigations, as well as neuroimaging studies should be made to diagnose and treat any underlying conditions.