The weight-based heparin dosing nomogram compared with a "standard care" nomogram. A randomized controlled trial

OBJECTIVE

To determine whether an intravenous heparin dosing nomogram based on body weight achieves therapeutic anticoagulation more rapidly than a "standard care" nomogram.

DESIGN

Randomized controlled trial.

SETTING

Two community teaching hospitals in Phoenix, Arizona, and Rochester, New York.

PARTICIPANTS

One hundred fifteen patients requiring intravenous heparin treatment for venous or arterial thromboembolism or for unstable angina.

INTERVENTION

Patients were randomized to the weight-based nomogram (starting dose, 80 units/kg body weight bolus, 18 units/kg per hour infusion) or the standard care nomogram (starting dose, 5000-unit bolus, 1000 units per hour infusion). Activated partial thromboplastin time (APTT) values were monitored every 6 hours, and heparin dose adjustments were determined by the nomograms.

MEASUREMENTS

Activated partial thromboplastin times were measured using a widely generalizable laboratory method. The primary outcomes were the time to exceed the therapeutic threshold (APTT > 1.5 times the control) and the time to achieve therapeutic range (APTT, 1.5 to 2.3 times the control). Bleeding complications and recurrent thromboembolism were also compared.

RESULTS

Kaplan-Meier curves for the primary outcomes favored the weight-based nomogram (P < 0.001 for both). In the weight-based heparin group, 60 of 62 patients (97%) exceeded the therapeutic threshold within 24 hours, compared with 37 of 48 (77%) in the standard care group (P < 0.002). Only one major bleeding complication occurred (in a standard care patient). Recurrent thromboembolism was more frequent in the standard care group; relative risk, 5.0 (95% CI, 1.1 to 21.9).

CONCLUSIONS

The weight-based heparin nomogram is widely generalizable and has proved to be effective, safe, and superior to one based on standard practice.

Noninvasive imaging of in vivo blood flow velocity using optical Doppler tomography

We report the development of an optical technique for noninvasive imaging of in vivo blood flow dynamics and tissue structures with high spatial resolution (2-10 microm) in biological systems. The technique is based on optical Doppler tomography (ODT), which combines Doppler velocimetry with optical coherence tomography to measure blood flow velocity at discrete spatial locations. The exceptionally high resolution of ODT permits noninvasive in vivo imaging of both blood microcirculation and tissue structures surrounding the vessel, which has significance for biomedical research and clinical applications. Tomographic imaging of in vivo blood flow velocity in the chick chorioallantoic membrane and in rodent skin is demonstrated.

Cardiotoxicity associated with the cancer therapeutic agent sunitinib malate

BACKGROUND

In the pivotal phase III metastatic renal cell carcinoma trial, updated data indicates that 21% of sunitinib-treated patients experienced a decline in left ventricular ejection fraction to below normal. This cardiotoxicity was reported to be reversible and without clinical sequelae. We conducted a retrospective analysis of our institutional experience of cardiotoxicity with sunitinib after observing a high incidence of symptomatic heart failure.

PATIENTS AND METHODS

Patients receiving sunitinib at Stanford University from 1 July 2004 to 1 July 2007 were identified. Medical records were reviewed and those patients experiencing symptomatic grade 3/4 left ventricular systolic dysfunction were identified. Potential cardiac risk factors were analyzed.

RESULTS

Forty-eight patients treated with sunitinib were assessable. Seven patients experienced symptomatic grade 3/4 left ventricular dysfunction 22-435 days after initiation of sunitinib. Three patients had persistent cardiac dysfunction after discontinuation of sunitinib and initiation of heart failure therapy. A history of congestive heart failure, coronary artery disease and lower body mass index were factors associated with increased risk.

CONCLUSIONS

Among patients treated with sunitinib at our institution, 15% developed symptomatic grade 3/4 heart failure. Future studies of sunitinib-related cardiotoxicity are urgently needed, particularly as the oncologic indications for this drug continue to expand.

Vitamin A controls epithelial/mesenchymal interactions through Ret expression

Mutations or rearrangements in the gene encoding the receptor tyrosine kinase RET result in Hirschsprung disease, cancer and renal malformations. The standard model of renal development involves reciprocal signaling between the ureteric bud epithelium, inducing metanephric mesenchyme to differentiate into nephrons, and metanephric mesenchyme, inducing the ureteric bud to grow and branch. RET and GDNF (a RET ligand) are essential mediators of these epithelial-mesenchymal interactions. Vitamin A deficiency has been associated with widespread embryonic abnormalities, including renal malformations. The vitamin A signal is transduced by nuclear retinoic acid receptors (RARs). We previously showed that two RAR genes, Rara and Rarb2, were colocalized in stromal mesenchyme, a third renal cell type, where their deletion led to altered stromal cell patterning, impaired ureteric bud growth and downregulation of Ret in the ureteric bud. Here we demonstrate that forced expression of Ret in mice deficient for both Rara and Rarb2 (Rara(-/-)Rarb2(-/-)) genetically rescues renal development, restoring ureteric bud growth and stromal cell patterning. Our studies indicate the presence of a new reciprocal signaling loop between the ureteric bud epithelium and the stromal mesenchyme, dependent on Ret and vitamin A. In the first part of the loop, vitamin-A-dependent signals secreted by stromal cells control Ret expression in the ureteric bud. In the second part of the loop, ureteric bud signals dependent on Ret control stromal cell patterning.

Expression of green fluorescent protein in the ureteric bud of transgenic mice: a new tool for the analysis of ureteric bud morphogenesis

The growth and branching of the ureteric bud is a complex process that is ultimately responsible for the organization of the collecting duct system as well as the number of nephrons in the metanephric kidney. While the genes involved in the regulation of this process have begun to be elucidated, our understanding of the cellular and molecular basis of ureteric bud morphogenesis remains rudimentary. Furthermore, the timing and sequence of branching and elongation that gives rise to the collecting system of the kidney can only be inferred from retrospective staining or microdissection of fixed preparations. To aid in the investigation of these issues, we developed strains of transgenic mice in which a green fluorescent protein (GFP) is expressed in the ureteric bud under the control of the Hoxb7 promoter. In these mice, GFP is expressed in every branch of the ureteric bud throughout renal development, and in its derivative epithelia in the adult kidney. As GFP fluorescence can be easily visualized in living tissue, this allows the dynamic pattern of ureteric bud growth and branching to be followed over several days when the kidneys are cultured in vitro. Using confocal microscopy, branching of the ureteric bud in all three dimensions can be analyzed. These mice represent an extremely powerful tool to characterize the normal patterns of ureteric bud morphogenesis and to investigate the response of the bud to growth factors, matrix elements, and other agents that regulate its growth and branching.

Integration of spatial and single-cell transcriptomic data elucidates mouse organogenesis

Molecular profiling of single cells has advanced our knowledge of the molecular basis of development. However, current approaches mostly rely on dissociating cells from tissues, thereby losing the crucial spatial context of regulatory processes. Here, we apply an image-based single-cell transcriptomics method, sequential fluorescence in situ hybridization (seqFISH), to detect mRNAs for 387 target genes in tissue sections of mouse embryos at the 8-12 somite stage. By integrating spatial context and multiplexed transcriptional measurements with two single-cell transcriptome atlases, we characterize cell types across the embryo and demonstrate that spatially resolved expression of genes not profiled by seqFISH can be imputed. We use this high-resolution spatial map to characterize fundamental steps in the patterning of the midbrain-hindbrain boundary (MHB) and the developing gut tube. We uncover axes of cell differentiation that are not apparent from single-cell RNA-sequencing (scRNA-seq) data, such as early dorsal-ventral separation of esophageal and tracheal progenitor populations in the gut tube. Our method provides an approach for studying cell fate decisions in complex tissues and development.

Differential activities of the RET tyrosine kinase receptor isoforms during mammalian embryogenesis

The RET receptor tyrosine kinase has a critical role in kidney organogenesis and the development of the enteric nervous system. Two major isoforms, RET9 and RET51, differ in the amino acid sequence of the C-terminal tail as a result of alternative splicing. To determine the roles of these isoforms in vivo, we used targeted mutagenesis to generate mice that express either RET9 or RET51. Monoisoformic RET9 mice, which lack RET51, are viable and appear normal. In contrast, monoisoformic RET51 animals, which lack RET9, have kidney hypodysplasia and lack enteric ganglia from the colon. To study the differential activities of the two RET isoforms further, we generated transgenic mice expressing ligand-dependent and constitutively active forms of RET9 or RET51 under the control of the Hoxb7 regulatory sequences. Such RET9 transgenes are capable of rescuing the kidney agenesis in RET-deficient mice or causing kidney hypodysplasia in wild-type animals. In contrast, similar RET51 transgenes fail to rescue the kidney agenesis or cause hypodysplasia. Our findings show that RET9 and RET51 have different signaling properties in vivo and define specific temporal and spatial requirements of c-Ret function during renal development and histogenesis of the enteric nervous system.

Human interferon lambda-1 (IFN-lambda1/IL-29) modulates the Th1/Th2 response

Interferon lambda-1 (IFN-lambda1/IL-29) is a member of the Type-III interferon family, which contains three ligands: IFN-lambda1, 2 and 3. These three ligands use the same unique heterodimeric receptor composed of CRF2-12 (IFN-lambda-R1/IL-28Ralpha) and CRF2-4 (IL10-R-beta) chains. Like their close relatives, the Type-I interferons, IFN-lambda1, 2 and 3, promote the phosphorylation of STAT1 and STAT2, induce the ISRE3 complex, elevate OAS and MxA expression and exhibit antiviral activity in vitro. Their use of the IL10-R-beta chain and their ability to phosphorylate STAT3, STAT4 and STAT5 suggested that they may also exhibit immunomodulatory activity; their antiviral action led us to hypothesize that this activity might be directed toward the Th1/Th2 system. Here, we have demonstrated that IFN-lambda1 altered the activity of Th cells in three separate experimental systems: (i) mitogen stimulation, (ii) mixed-lymphocyte reaction (MLR) and (iii) stimulation of naive T cells by monocyte-derived dendritic cells (mDC). In Con-A stimulation assays, the inclusion of IFN-lambda1 consistently led to markedly diminished levels of secreted interleukin (IL-13) with occasional coincident, modest elevation of secreted IFN-gamma. IL-13 secretion was 100-fold more sensitive to IFN-lambda1 than was IFN-gamma secretion. These observations were also made in the allogeneic two-way MLR. IFN-lambda1 was able to alter cytokine-mediated Th biasing and when naive T cells were exposed to allogeneic mDC that had been matured in the presence of IFN-lambda1, secreted IL-13 was again markedly and consistently reduced, whereas secreted IFN-gamma was largely unaltered. These functions were independent of IL-10. Our data support a hitherto unsuspected role for IFN-lambda1 in modulating the development of Th1 and Th2 cells, with an apparent emphasis on the diminution of IL-13 secretion.

Ultra-Low-Dose 18F-Florbetaben Amyloid PET Imaging Using Deep Learning with Multi-Contrast MRI Inputs

Purpose To reduce radiotracer requirements for amyloid PET/MRI without sacrificing diagnostic quality by using deep learning methods. Materials and Methods Forty data sets from 39 patients (mean age ± standard deviation [SD], 67 years ± 8), including 16 male patients and 23 female patients (mean age, 66 years ± 6 and 68 years ± 9, respectively), who underwent simultaneous amyloid (fluorine 18 [18F]-florbetaben) PET/MRI examinations were acquired from March 2016 through October 2017 and retrospectively analyzed. One hundredth of the raw list-mode PET data were randomly chosen to simulate a low-dose (1%) acquisition. Convolutional neural networks were implemented with low-dose PET and multiple MR images (PET-plus-MR model) or with low-dose PET alone (PET-only) as inputs to predict full-dose PET images. Quality of the synthesized images was evaluated while Bland-Altman plots assessed the agreement of regional standard uptake value ratios (SUVRs) between image types. Two readers scored image quality on a five-point scale (5 = excellent) and determined amyloid status (positive or negative). Statistical analyses were carried out to assess the difference of image quality metrics and reader agreement and to determine confidence intervals (CIs) for reading results. Results The synthesized images (especially from the PET-plus-MR model) showed marked improvement on all quality metrics compared with the low-dose image. All PET-plus-MR images scored 3 or higher, with proportions of images rated greater than 3 similar to those for the full-dose images (-10% difference [eight of 80 readings], 95% CI: -15%, -5%). Accuracy for amyloid status was high (71 of 80 readings [89%]) and similar to intrareader reproducibility of full-dose images (73 of 80 [91%]). The PET-plus-MR model also had the smallest mean and variance for SUVR difference to full-dose images. Conclusion Simultaneously acquired MRI and ultra-low-dose PET data can be used to synthesize full-dose-like amyloid PET images. © RSNA, 2018 Online supplemental material is available for this article. See also the editorial by Catana in this issue.

Oximetry of retinal vessels by dual-wavelength imaging: calibration and influence of pigmentation

A method for noninvasive measurement of Hb O2 saturation (SO2) in retinal blood vessels by digital imaging was developed and tested. Images of vessels were recorded at O2-sensitive and O2-insensitive wavelengths (600 and 569 nm, respectively) by using a modified fundus camera with an image splitter coupled to an 18-bit digital camera. Retinal arterial SO2 was varied experimentally by having subjects breathe mixtures of O2 and N2 while systemic arterial SO2 was monitored with a pulse oximeter. Optical densities (ODs) of vascular segments were determined using a computer algorithm to track the path of reflected light intensity along vessels. During graded hypoxia the OD ratio (ODR = OD600/OD569) bore an inverse linear relationship to systemic SO2. Compensation for the influence of choroidal pigmentation significantly reduced variation in the arterial SO2 measurements among subjects. An O2 sensitivity of 0.00504 +/- 0.00029 (SE) ODR units/%SO2 was determined. Retinal venous SO2 at normoxia was 55 +/- 3.38% (SE). Breathing 100% O2 increased venous SO2 by 19.2 +/- 2.9%. This technique, when combined with blood flow studies in human subjects, will enable the study of retinal O2 utilization under experimental and various disease conditions.

Structural basis of the recognition of the dishevelled DEP domain in the Wnt signaling pathway

The DEP domain of Dishevelled (Dvl) proteins transduces signals to effector proteins downstream of Dvl in the Wnt pathway. Here we report that DEP-containing mutants inhibit Wnt-induced, but not Dvl-induced, activation of the transcription factor Lef-1. This inhibitory effect is weakened by a K434M mutation. Nuclear magnetic resonance spectroscopy revealed that the DEP domain of mouse Dvl1 comprises a three-helix bundle, a beta-hairpin 'arm' and two short beta-strands at the C-terminal region. Lys 434 is located at the tip of the beta-hairpin 'arm'. Based on our findings, we conclude that DEP interacts with regulators upstream of Dvl via a strong electric dipole on the molecule's surface created by Lys 434, Asp 445 and Asp 448; the electric dipole and the putative membrane binding site are at two different locations.

Progressive decrease in bone density over 10 years of androgen deprivation therapy in patients with prostate cancer

OBJECTIVES

Several reports suggest an increased incidence of osteoporosis and concomitant fractures in men receiving androgen deprivation therapy (ADT) for prostate cancer. We sought to estimate the longitudinal effects of ADT on loss of bone density in this cross-sectional study.

METHODS

Hip and spine bone mineral density (BMD) studies were performed by dual-energy x-ray absorptiometry on 36 patients with prostate cancer. The year 0 cohort (n = 8) consisted of patients who had not yet begun planned ADT. These men were compared to patients receiving ADT who underwent BMD evaluation at year 2 (n = 6), year 4 (n = 7), year 6 (n = 5), year 8 (n = 5), and year 10 (n = 5) of therapy. All BMD values for the patients with prostate cancer were compared to age-matched control subjects.

RESULTS

Hip BMD was significantly lower in patients on ADT (mean BMD 0.802 g/cm(2)) compared with those not on ADT (mean BMD 0.935 g/cm(2)). Patients at year 0 had hip and spine BMD similar to age-matched control subjects. There was a significant trend for decreased hip BMD with increasing years of ADT (r = 0.46, P = 0.00008). This relationship was more dramatic when hip BMD at each time point was compared to age-matched control subjects (r = 0.55, P = 0.5 x 10(-16)). This bone loss was evident even up to year 10. BMD loss was more dramatic in patients who had undergone surgical castration than those receiving medical ADT (P = 0.08). Patients on intermittent ADT had similar BMD loss as patients on continuous ADT at year 2 and year 4 but demonstrated less bone loss at year 6 (P = 0.07) despite equivalently low testosterone levels.

CONCLUSIONS

There is diminished BMD with increasing duration of ADT. Continuous ADT and surgical castration may be more deleterious than medical therapy, particularly when the medical therapy is given in an intermittent fashion.

The antiandrogen withdrawal syndrome. Experience in a large cohort of unselected patients with advanced prostate cancer

BACKGROUND

Flutamide withdrawal has been reported to be therapeutically efficacious for patients with hormone-refractory prostate cancer, with a reported prostate specific antigen (PSA) response rate of 29%.

METHODS

to evaluate the results of flutamide withdrawal in a large group of unselected patients, the medical records of 107 consecutive patients with metastatic prostate cancer who developed progressive disease while receiving flutamide therapy were reviewed retrospectively. Flutamide withdrawal was undertaken at the time of disease progression.

RESULTS

Eighty-two patients were evaluable. Of these, three had a > 80% fall in PSA value, and another nine had a > 50% decrease, for a response proportion of 14.6% (95% confidence interval 7.8%-24.2%). The median response duration was 3.5 months (range, 1-12+ months). Eight of patients treated with combined androgen blockade at the time of diagnosis of metastatic disease had a response (14%), whereas 4/25 responses (16%) were noted in patients in whom flutamide was added later, at the time of first progression. When patients who responded were compared with patients who did not respond, there was not a significant difference in age, pretreatment PSA level, type of gonadal androgen deprivation, or the likelihood of prior combined androgen blockade versus late addition of flutamide. The duration of prior therapy with flutamide was longer in patients who responded (21.5 vs. 12.0 months).

CONCLUSIONS

These findings confirm the flutamide withdrawal phenomenon in a large group of unselected patients, although its frequency is not as high as previously reported. In contrast to earlier reports, whether patients have had initial hormonal therapy with combined androgen blockade or monotherapy does not appear to be predictive of the likelihood of response to antiandrogen withdrawal.

Outcomes of patients with metastatic renal cell carcinoma that do not meet eligibility criteria for clinical trials

BACKGROUND

Targeted therapies in metastatic renal cell carcinoma (mRCC) have been approved based on registration clinical trials that have strict eligibility criteria. The clinical outcomes of patients treated with targeted agents but are ineligible for trials are unknown.

PATIENTS AND METHODS

mRCC patients treated with vascular endothelial growth factor-targeted therapy were retrospectively deemed ineligible for clinical trials (according to commonly used inclusion/exclusion criteria) if they had a Karnofsky performance status (KPS) <70%, nonclear-cell histology, brain metastases, hemoglobin ≤9 g/dl, creatinine >2× the upper limit of normal, corrected calcium ≥12 mg/dl, platelet count of <100 × 10(3)/uL, or neutrophil count <1500/mm(3).

RESULTS

Overall, 768 of 2210 (35%) patients in the International Metastatic RCC Database Consortium (IMDC) were deemed ineligible for clinical trials by the above criteria. Between ineligible versus eligible patients, the response rate, median progression-free survival (PFS) and median overall survival of first-line targeted therapy were 22% versus 29% (P = 0.0005), 5.2 versus 8.6 months, and 12.5 versus 28.4 months (both P < 0.0001), respectively. Second-line PFS (if applicable) was 2.8 months in the trial ineligible versus 4.3 months in the trial eligible patients (P = 0.0039). When adjusted by the IMDC prognostic categories, the HR for death between trial ineligible and trial eligible patients was 1.55 (95% confidence interval 1.378-1.751, P < 0.0001).

CONCLUSIONS

The number of patients that are ineligible for clinical trials is substantial and their outcomes are inferior. Specific trials addressing the unmet needs of protocol ineligible patients are warranted.

Imaging thermally damaged tissue by Polarization Sensitive Optical Coherence Tomography

Polarization Sensitive Optical Coherence Tomography (PS- OCT) was used to image the reduction of birefringence in biological tissue due to thermal damage. Through simultaneous detection of the amplitude of signal fringes in orthogonal polarization states formed by interference of light backscattered from turbid media and a mirror in the reference arm of a Michelson interferometer, changes in the polarization due to the optical phase delay between light propagating along the fast and slow axes of birefringent media were measured. Inasmuch as fibrous structures in many biological tissues in uence the polarization state of light backscattered, PS-OCT is a potentially useful technique to image the structural properties of turbid biological materials. Birefringence of collagen, a constituent of many biological tissues, is reduced by denaturation that takes place at a temperature between 56-65 0 C, thus providing an "optical marker" for thermal damage. Images showing reduction of birefringence due to thermal damage in porcine tendon and skin are presented and demonstrate the potential of PS-OCT for burn depth assessment.

Epstein-Barr Virus DNA recombination and loss in sporadic Burkitt's lymphoma

Epstein-Barr virus (EBV) antigens in tumor tissue define associations of virus with human malignancies and provide clues as to mechanisms of viral oncogenesis. In Burkitt's lymphoma, EBV markers are absent from 85% of sporadic cases and 4% of endemic (African) cases, raising questions as to the exact role EBV in the disease. Standard screening criteria may be insufficient to determine the EBV status of all tumors. One of 9 tumors from American patients expressed EBV nuclear antigen 1 (EBNA1) and contained standard episomal EBV DNA, making this series consistent with the 15% EBV association traditionally ascribed to sporadic Burkitt's lymphoma. Surprisingly, 3 tumors without detectable EBNA1 contained partial EBV genomes. Identification of defective, integrated viral DNA in some tumors indicates greater involvement of virus in sporadic Burkitt's lymphoma than previously documented and suggests a process of viral DNA rearrangement and loss during malignant progression most consistent with an initiating role for EBV in tumorigenesis.

Structure, bonding, and magnetism in manganese clusters

We investigate the structures and magnetic properties of small Mn(n) clusters in the size range of 2-13 atoms using first-principles density functional theory. We arrive at the lowest energy structures for clusters in this size range by simultaneously optimizing the cluster geometries, total spins, and relative orientations of individual atomic moments. The results for the net magnetic moments for the optimal clusters are in good agreement with experiment. The magnetic behavior of Mn(n) clusters in the size range studied in this work ranges from ferromagnetic ordering (large net cluster moment) for the smallest (n=2, 3, and 4) clusters to a near degeneracy between ferromagnetic and antiferromagnetic solutions in the vicinity of n=5 and 6 to a clear preference for antiferromagnetic (small net cluster moment) ordering at n=7 and beyond. We study the details of this evolution and present a picture in which bonding in these clusters predominantly occurs due to a transfer of electrons from antibonding 4s levels to minority 3d levels.

Parenteral gene therapy with p53 inhibits human breast tumors in vivo through a bystander mechanism without evidence of toxicity

Mutations of the p53 tumor suppressor gene are the most frequently observed genetic lesion in human cancer. Previously, we found that multiple intravenous injections of a liposome:p53 complex inhibited the growth of a malignant human breast cancer cell line that was implanted into nude mice. In the present study, we evaluated the toxicity of the liposome:p53 complex and the mechanism of this in vivo treatment in reducing tumor growth. Intravenously delivered liposome:p53 complex at dosages sufficient to inhibit human breast cancer in nude mice showed no evidence of toxicity. Clinical chemistries, complete blood counts, and histopathologic examination of various organs from the p53-treated groups did not demonstrate any difference from the control groups. To elucidate the mechanism by which the liposome:p53 complex inhibits cancer, the transfection efficiency of a liposome:chloramphenicol acetyltransferase (CAT) complex into the tumor was determined. Interestingly, less than 5% of the tumor was transfected with a liposome:CAT complex. A mechanism that could account for p53 reduction of tumor size and a low transfection efficiency is inhibition of angiogenesis. After one treatment, we found that the liposome:p53 complex reduced the number of blood vessels in the p53-treated group by approximately 60% compared to the control group (p < 0.001). The close correlation between the antitumor effect of p53 and the reduction of blood vessel density in the tumor suggests that p53 effects are mediated, at least in part, by an antiangiogenesis mechanism.

Dominant effects of RET receptor misexpression and ligand-independent RET signaling on ureteric bud development

During kidney development, factors from the metanephric mesenchyme induce the growth and repeated branching of the ureteric bud, which gives rise to the collecting duct system and also induces nephrogenesis. One signaling pathway known to be required for this process includes the receptor tyrosine kinase RET and co-receptor GFR(α)-1, which are expressed in the ureteric bud, and the secreted ligand GDNF produced in the mesenchyme. To examine the role of RET signaling in ureteric bud morphogenesis, we produced transgenic mice in which the pattern of RET expression was altered, or in which a ligand-independent form of RET kinase was expressed. The Hoxb7 promoter was used to express RET throughout the ureteric bud branches, in contrast to its normal expression only at the bud tips. This caused a variable inhibition of ureteric bud growth and branching reminiscent of, but less severe than, the RET knockout phenotype. Manipulation of the level of GDNF, in vitro or in vivo, suggested that this defect was due to insufficient rather than excessive RET signaling. We propose that RET receptors expressed ectopically on ureteric bud trunk cells sequester GDNF, reducing its availability to the normal target cells at the bud tips. When crossed to RET knockout mice, the Hoxb7/RET transgene, which encoded the RET9 isoform, supported normal kidney development in some RET−/− animals, indicating that the other major isoform, RET51, is not required in this organ. Expression of a Hoxb7/RET-PTC2 transgene, encoding a ligand-independent form of RET kinase, caused the development of abnormal nodules, outside the kidney or at its periphery, containing branched epithelial tubules apparently formed by deregulated growth of the ureteric bud. This suggests that RET signaling is not only necessary but is sufficient to induce ureteric bud growth, and that the orderly, centripetal growth of the bud tips is controlled by the spatially and temporally regulated expression of GDNF and RET.

Comparative analysis of the safety and efficacy of transcatheter arterial chemoembolization and yttrium-90 radioembolization in patients with unresectable hepatocellular carcinoma

PURPOSE

To compare retrospectively the safety and efficacy of yttrium-90 ((90)Y) radioembolization with the safety and efficacy of chemoembolization in patients with unresectable hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Survival and complication rates were evaluated for patients with HCC who underwent chemoembolization or radioembolization at a single institution between August 2007 and April 2010. Complications were graded according to a standardized grading system for embolization procedures. Survival was determined via the Kaplan-Meier method, and multivariable analysis for factors affecting survival was performed.

RESULTS

This study included 73 patients with HCC who underwent index embolization with radioembolization (n = 38; 52.1%) or chemoembolization (n = 35; 47.9%). The two patient populations were similar in terms of demographics, etiology of cirrhosis, functional status, tumor characteristics, Child-Pugh class, previous liver-directed therapy, and number of patients with bilirubin > 2.0 mg/dL. There was no significant difference in survival between the radioembolization (median 8.0 months) and chemoembolization (median 10.3 months) cohorts (P = .33). Postembolization syndrome was significantly more severe in patients who underwent chemoembolization, which led to increased total hospitalization rates in these patients. The rates of other complications and rehospitalization were similar between groups. Increased age, Child-Pugh class B, hepatitis seropositivity, bilobar tumor distribution, tumor vascular invasion, and presence of extrahepatic metastases were associated with reduced patient survival.

CONCLUSIONS

Patients treated with radioembolization did not show a survival advantage over patients treated with chemoembolization. However, patients who underwent chemoembolization had significantly higher rates of hospitalization as a result of postembolization syndrome.

In vitro effects of a high-molecular-weight heat-labile enterotoxin from enteroaggregative Escherichia coli

The pathogenic mechanisms of enteroaggregative Escherichia coli (EAggEC) infection are not fully elucidated. In this work we show that an ammonium sulfate precipitate of culture supernatant of EAggEC strain 049766 increased the potential difference (PD) and the short-circuit current (Isc) in rat jejunal preparations mounted in Ussing chambers. The precipitate contained two major proteins of 108 and 116 kDa, which were partially copurified by chromatography in DEAE-cellulose. This chromatographic fraction (peak I) increased jejunal PD and Isc in a dose-dependent manner, accompanied by a decrease in tissue electrical resistance. These effects were inhibited by incubation of peak I at 75 degreesC for 15 min or for 1 h with proteinase K at 37 degreesC. Rabbit polyclonal antibodies against peak I containing both the 108- and 116-kDa proteins inhibited the enterotoxic effect. Specific polyclonal antibodies raised against the 108-kDa but not against the 116-kDa protein inhibited the enterotoxic effect, suggesting that the 108-kDa protein is the active toxic species. Moreover, another EAggEC strain (065126) producing the 116-kDa protein but not the 108-kDa protein had no effect on rat jejunal mucosa in the Ussing chamber. The >100-kDa fraction derived from prototype EAggEC strain 042, which also expressed both 108- and 116-kDa proteins, also produced an enterotoxic effect on rat jejunal preparations in Ussing chambers; however, the same strain cured of its 65-MDa adherence plasmid did not. A subclone derived from the 65-MDa plasmid expressing the 108-kDa toxin (and not the 116-kDa protein) elicited rises in Isc. Tissue exposed to any preparation containing the 108-kDa toxin exhibited similar histopathologic changes, characterized by increased mucus release, exfoliation of cells, and development of crypt abscesses. Our data suggest that some EAggEC strains produce a ca. 108-kDa enterotoxin/cytotoxin which is encoded on the large virulence plasmid.

Retinal oxygen consumption during hyperglycemia in patients with diabetes without retinopathy

OBJECTIVE

This study aimed to determine whether retinal oxygen consumption in patients with diabetes without retinopathy is affected by acute changes in blood glucose.

DESIGN

The study design was a nonrandomized, interventional clinical study.

PARTICIPANTS

The study consisted of 12 patients with diabetes without ophthalmoscopically visible diabetic retinopathy whose ages were 20 to 59 years (mean, 33.7 years).

INTERVENTION

Retinal vessel oximetry was performed on subjects during normoglycemia and during acutely induced hyperglycemia. Hyperglycemia was achieved with the ingestion of an oral glucose load.

MAIN OUTCOME MEASURES

Changes in retinal arterial and venous blood oxygen saturation resulting from systemic blood glucose changes were measured. Measurements were made using a noninvasive, two-wavelength digital imaging retinal vessel oximeter.

RESULTS

In each subject, the measured retinal venous blood oxygen saturation decreased significantly during hyperglycemia. The amount of decrease in venous oxygen saturation associated with hyperglycemia was positively correlated with the duration of diabetes. The measured retinal arterial oxygen saturation did not change significantly during hyperglycemia.

CONCLUSIONS

These results, taken with the observations of numerous other investigators that show increased blood flow during acute hyperglycemia, provide evidence of substantially increased retinal oxygen consumption during hyperglycemia. The results also complement previous observations of the effect of diabetes on retinal autoregulation.