Pyrazole-Based Lactate Dehydrogenase Inhibitors with Optimized Cell Activity and Pharmacokinetic Properties.

Lactate dehydrogenase (LDH) catalyzes the conversion of pyruvate to lactate, with concomitant oxidation of reduced nicotinamide adenine dinucleotide as the final step in the glycolytic pathway. Glycolysis plays an important role in the metabolic plasticity of cancer cells and has long been recognized as a potential therapeutic target. Thus, potent, selective inhibitors of LDH represent an attractive therapeutic approach. However, to date, pharmacological agents have failed to achieve significant target engagement in vivo, possibly because the protein is present in cells at very high concentrations. We report herein a lead optimization campaign focused on a pyrazole-based series of compounds, using structure-based design concepts, coupled with optimization of cellular potency, in vitro drug-target residence times, and in vivo PK properties, to identify first-in-class inhibitors that demonstrate LDH inhibition in vivo. The lead compounds, named NCATS-SM1440 (43) and NCATS-SM1441 (52), possess desirable attributes for further studying the effect of in vivo LDH inhibition.

Dynamic Imaging of LDH Inhibition in Tumors Reveals Rapid In Vivo Metabolic Rewiring and Vulnerability to Combination Therapy.

The reliance of many cancers on aerobic glycolysis has stimulated efforts to develop lactate dehydrogenase (LDH) inhibitors. However, despite significant efforts, LDH inhibitors (LDHi) with sufficient specificity and in vivo activity to determine whether LDH is a feasible drug target are lacking. We describe an LDHi with potent, on-target, in vivo activity. Using hyperpolarized magnetic resonance spectroscopic imaging (HP-MRSI), we demonstrate in vivo LDH inhibition in two glycolytic cancer models, MIA PaCa-2 and HT29, and we correlate depth and duration of LDH inhibition with direct anti-tumor activity. HP-MRSI also reveals a metabolic rewiring that occurs in vivo within 30 min of LDH inhibition, wherein pyruvate in a tumor is redirected toward mitochondrial metabolism. Using HP-MRSI, we show that inhibition of mitochondrial complex 1 rapidly redirects tumor pyruvate toward lactate. Inhibition of both mitochondrial complex 1 and LDH suppresses metabolic plasticity, causing metabolic quiescence in vitro and tumor growth inhibition in vivo.

Temple or Prison: Religious Beliefs and Attitudes Toward the Body.

Most research on religion and the body has focused on the relationship between broad dimensions of religion, such as religious commitment or religious orientation, and body image or eating behaviors. The present study extends existing research by examining two specific religiously influenced beliefs about the body within a Protestant Christian sample, radical dualism and sanctification, and by focusing on a wider range of attitudes toward the body. The view of radical dualism sees the body as corrupt and separate from oneself, while the view of sanctification sees the body as holy, worthy of respect, and integral to one's being. This study examined how both radically dualistic and sanctified views of the body relate to attitudes people hold about their bodies including body appreciation and two components of body objectification: self-surveillance and body shame. To date, none of these attitudes have been examined in relation to specific, nuanced religious beliefs about the body. Participants were 243 adults from a variety of Protestant denominations. Using an online survey system and self-report measures, participants indicated the degree to which they hold radically dualistic and sanctified views about their bodies as well as their attitudes toward their bodies. Radical dualism was found to be negatively related to body appreciation and positively related to body shame. Sanctification was found to predict body appreciation. Body shame mediated the relationship between religious beliefs about the body and self-surveillance. This study contributes to a greater understanding of how religiously based beliefs about the body are related to attitudes about the body.

Microglial priming through the lung-brain axis: the role of air pollution-induced circulating factors.

Air pollution is implicated in neurodegenerative disease risk and progression and in microglial activation, but the mechanisms are unknown. In this study, microglia remained activated 24 h after ozone (O3) exposure in rats, suggesting a persistent signal from lung to brain. Ex vivo analysis of serum from O3-treated rats revealed an augmented microglial proinflammatory response and ß-amyloid 42 (Aß42) neurotoxicity independent of traditional circulating cytokines, where macrophage-1 antigen-mediated microglia proinflammatory priming. Aged mice exhibited reduced pulmonary immune profiles and the most pronounced neuroinflammation and microglial activation in response to mixed vehicle emissions. Consistent with this premise, cluster of differentiation 36 (CD36)(-/-) mice exhibited impaired pulmonary immune responses concurrent with augmented neuroinflammation and microglial activation in response to O3 Further, aging glia were more sensitive to the proinflammatory effects of O3 serum. Together, these findings outline the lung-brain axis, where air pollutant exposures result in circulating, cytokine-independent signals present in serum that elevate the brain proinflammatory milieu, which is linked to the pulmonary response and is further augmented with age.-Mumaw, C. L., Levesque, S., McGraw, C., Robertson, S., Lucas, S., Stafflinger, J. E., Campen, M. J., Hall, P., Norenberg, J. P., Anderson, T., Lund, A. K., McDonald, J. D., Ottens, A. K., Block, M. L. Microglial priming through the lung-brain axis: the role of air pollution-induced circulating factors.

Muscle RING finger-1 promotes a maladaptive phenotype in chronic hypoxia-induced right ventricular remodeling.

Exposure to chronic hypoxia (CH) induces elevated pulmonary artery pressure/resistance, leading to an eventual maladaptive right ventricular hypertrophy (RVH). Muscle RING finger-1 (MuRF1) is a muscle-specific ubiquitin ligase that mediates myocyte atrophy and has been shown to play a role in left ventricular hypertrophy and altered cardiac bioenergetics in pressure overloaded hearts. However, little is known about the contribution of MuRF1 impacting RVH in the setting of CH. Therefore, we hypothesized that MuRF1 deletion would enhance RVH compared to their wild-type littermates, while cardiac-specific overexpression would reduce hypertrophy following CH-induced pulmonary hypertension. We assessed right ventricular systolic pressure (RVSP), right ventricle to left ventricle plus septal weight ratio (RV/LV+S) and hematocrit (Hct) following a 3-wk isobaric CH exposure. Additionally, we conducted dual-isotope SPECT/CT imaging with cardiac function agent 201Tl-chloride and cell death agent 99mTc-annexin V. Predictably, CH induced pulmonary hypertension, measured by increased RVSP, RV/LV+S and Hct in WT mice compared to normoxic WT mice. Normoxic WT and MuRF1-null mice exhibited no significant differences in RVSP, RV/LV+S or Hct. CH-induced increases in RVSP were also similar between WT and MuRF1-null mice; however, RV/LV+S and Hct were significantly elevated in CH-exposed MuRF1-null mice compared to WT. In cardiac-specific MuRF1 overexpressing mice, RV/LV+S increased significantly due to CH exposure, even greater than in WT mice. This remodeling appeared eccentric, maladaptive and led to reduced systemic perfusion. In conclusion, these results are consistent with an atrophic role for MuRF1 regulating the magnitude of right ventricular hypertrophy following CH-induction of pulmonary hypertension.

Sex disparities in pre-hospital and hospital treatment of ST-segment elevation myocardial infarction.

OBJECTIVE: To determine whether sex disparities exist in pre-hospital and hospital time to treatment in patients with ST-segment elevation myocardial infarction (STEMI). BACKGROUND: Evidence suggests that women experience poorer quality of care for STEMI. METHODS: A retrospective cohort study was conducted on 177 consecutive patients with STEMI who received primary percutaneous coronary intervention at a rural, tertiary medical center between January 2006 and October 2009. A subgroup analysis was conducted to evaluate time to treatment during a period of no-focused process improvement compared with a time period of focused, non­sex-specific process improvement; the post period included implementation of the STEMI process upgrade (STEP-UP) quality-improvement (QI) program. RESULTS: Median first-emergency-medical-services-contact-to-balloon (E2B) angioplasty time was significantly longer for women compared with men. A Cox proportional hazards model revealed that men had a significantly shorter E2B time than women. After adjustment for differences between sex groups at presentation, the effect of sex on E2B was no longer statistically significant. A similar effect was observed in door-to-balloon (D2B) angioplasty time. The subgroup analysis revealed that from baseline, both men and women experienced improvement in E2B time after implementation of the STEP-UP QI program. Men and women also experienced improvement in D2B time after implementation of the STEP-UP QI program. CONCLUSIONS: Women with STEMI experienced significantly longer E2B and D2B times compared with men with STEMI, although these differences did not persist after adjustment for differences between sex groups at presentation. In addition to standard STEMI-care QI practices, sex-specific processes and interventions at the systems level may be needed to improve time to treatment for women with STEMI.

Longitudinal in vivo SPECT/CT imaging reveals morphological changes and cardiopulmonary apoptosis in a rodent model of pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) has a complex pathogenesis involving both heart and lungs. Animal models can reflect aspects of the human pathology and provide insights into the development and underlying mechanisms of disease. Because of the variability of most animal models of PAH, serial in vivo measurements of cardiopulmonary function, morphology, and markers of pathology can enhance the value of such studies. Therefore, quantitative in vivo SPECT/CT imaging was performed to assess cardiac function, morphology and cardiac perfusion utilizing (201)Thallium ((201)Tl) in control and monocrotaline-treated rats. In addition, lung and heart apoptosis was examined with (99m)Tc-Annexin V ((99m)Tc-Annexin) in these cohorts. Following baseline imaging, rats were injected with saline or monocrotaline (50 mg/kg, i.p.) and imaged weekly for 6 weeks. To assess a therapeutic response in an established pulmonary hypertensive state, a cohort of rats received resveratrol in drinking water (3 mg/kg/day) on days 28-42 post-monocrotaline injection to monitor regression of cardiopulmonary apoptosis. PAH in monocrotaline-treated rats was verified by conventional hemodynamic techniques on day 42 (right ventricular systolic pressure (RSVP) = 66.2 mmHg in monocrotaline vs 28.8 mmHg in controls) and in terms of right ventricular hypertrophy (RV/LVS = 0.70 in monocrotaline vs 0.32 in controls). Resveratrol partially reversed both RVSP (41.4 mmHg) and RV/LVS (0.46), as well as lung edema and RV contractility +dP/dt(max). Serial (99m)Tc-Annexin V imaging showed clear increases in pulmonary and cardiac apoptosis when compared to baseline, which regressed following resveratrol treatment. Monocrotaline induced modest changes in whole-heart perfusion as assessed by (201)TI imaging and cardiac morphological changes consistent with septal deviation and enlarged RV. This study demonstrates the utility of functional in vivo SPECT/CT imaging in rodent models of PAH and further confirms the efficacy of resveratrol in reversing established monocrotaline-induced PAH presumably by attenuation of cardiopulmonary apoptosis.

Regional particle size dependent deposition of inhaled aerosols in rats and mice.

CONTEXT: The current data analysis tools in nuclear medicine have not been used to evaluate intra organ regional deposition patterns of pharmaceutical aerosols in preclinical species. OBJECTIVE: This study evaluates aerosol deposition patterns as a function of particle size in rats and mice using novel image analysis techniques. MATERIALS AND METHOD: Mice and rats were exposed to radiolabeled polydisperse aerosols at 0.5, 1.0, 3.0, and 5.0 µm MMAD followed by SPECT/CT imaging for deposition analysis. Images were quantified for both macro deposition patterns and regional deposition analysis using the LRRI-developed Onion Model. RESULTS: The deposition fraction in both rats and mice was shown to increase as the particle size decreased, with greater lung deposition in rats at all particle sizes. The Onion Model indicated that the smaller particle sizes resulted in increased peripheral deposition. DISCUSSION: These data contrast the commonly used 10% deposition fraction for all aerosols between 1.0 and 5.0 µm and indicate that lung deposition fraction in this range does change with particle size. When compared to historical data, the 1.0, 3.0, and 5.0 µm particles result in similar lung deposition fractions; however, the 0.5 µm lung deposition fraction is markedly different. This is probably caused by the current aerosols that were polydisperse to reflect current pharmaceutical aerosols, while the historical data were generated with monodisperse aerosols. CONCLUSION: The deposition patterns of aerosols between 0.5 and 5.0 µm showed an increase in both overall and peripheral deposition as the particle size decreased. The Onion Model allows a more complex analysis of regional deposition in preclinical models.

Primary percutaneous coronary intervention for patients presenting with ST-segment elevation myocardial infarction: process improvement in a rural ST-segment elevation myocardial infarction receiving center.

BACKGROUND: Rural ST-segment elevation myocardial infarction (STEMI) care networks may be particularly disadvantaged in achieving a door-to-balloon time (D2B) of less than or equal to 90 minutes recommended in current guidelines. ST-ELEVATION MYOCARDIAL INFARCTION PROCESS UPGRADE PROJECT: A multidisciplinary STEMI process upgrade group at a rural percutaneous coronary intervention center implemented evidence-based strategies to reduce time to electrocardiogram (ECG) and D2B, including catheterization laboratory activation triggered by either a prehospital ECG demonstrating STEMI or an emergency department physician diagnosing STEMI, single-call catheterization laboratory activation, catheterization laboratory response time less than or equal to 30 minutes, and prompt data feedback. EVALUATING SUCCESS: An ongoing regional STEMI registry was used to collect process time intervals, including time to ECG and D2B, in a consecutive series of STEMI patients presenting before (group 1) and after (group 2) strategy implementation. Significant reductions in time to first ECG in the emergency department and D2B were seen in group 2 compared with group 1. CONCLUSIONS: Important improvement in the process of acute STEMI patient care was accomplished in the rural percutaneous coronary intervention center setting by implementing evidence-based strategies.

Primary percutaneous coronary intervention for patients presenting with ST-elevation myocardial infarction: process improvements in rural prehospital care delivered by emergency medical services.

BACKGROUND: Safe and effective patient care for ST-elevation myocardial infarction (STEMI) relies on prompt emergency medical service (EMS) and established care coordination with receiving hospitals to conduct primary percutaneous coronary intervention (PCI). Likewise, a new emphasis has been placed on first medical contact-to-balloon (E2B) times as opposed to door-to-balloon times, identifying prehospital care as an important contributing factor for high-quality STEMI care. Therefore, we evaluated EMS processes of care before and after a period of continuous quality improvement to improve E2B times in our rural tertiary care medical center. METHODS: A retrospective, consecutive cohort study was conducted on 177 patients who received primary PCI at Dartmouth-Hitchcock Medical Center, a rural hospital, from January 1, 2006 to October 31, 2009. This cohort was stratified from January 1, 2008 to May 1, 2008 (n = 88) and May 1, 2008 to October 31, 2009 (n = 89), to acknowledge periods of no improvement (pre) and continuous quality improvement (post) in STEMI care. Primary outcome measures included frequency of non-PCI-capable hospital bypass, E2B, and frequency of prehospital electrocardiogram (ECG) and cardiac catheterization laboratory (CCL) activation. Descriptive statistics and log-rank tests were used to determine whether measures differed significantly by time period. A time-to-event analysis was conducted using a Cox proportional hazards model to assess the impact of outcomes measures on E2B pre/post-May 1, 2008. RESULTS: Patients who presented before May 1, 2008 had longer E2B times compared with patients in the post-May 1, 2008 cohort (145.1 minutes vs 115.2 minutes, t test P = .01). A log-rank test confirmed this (pre: 130 minutes vs post: 106 minutes, χ(2) = 5.3, log-rank P = .02). Similarly, patients who presented before May 1, 2008 had lower percentages of prehospital ECGs (49% vs 80%, P = .001) and CCL activations (4% vs 32%, P < .001). When prehospital ECGs (140 minutes vs 106 minutes, χ(2) = 5.9, log-rank P = .01) or CCL activations (125 minutes vs 98 minutes, χ(2) = 4.2, log-rank P = .04) were conducted, E2B times were significantly reduced. Patients who received both prehospital ECGs and prehospital CCL activations had significantly reduced E2B times compared with those who did not (125 minutes vs 91 minutes, χ(2) = 4.8, P = .02). CONCLUSIONS: The time saving benefits of prehospital ECGs may not be fully realized unless prehospital CCL activations also occur. EMS providers achieved further reductions in median E2B of approximately 24 minutes when prehospital ECGs were combined with prehospital CCL activation. Every effort should be made by PCI-capable medical centers to assess prehospital STEMI care and to integrate EMS providers into regional STEMI care quality improvement initiatives and education.

A performance evaluation of 90Y dose-calibrator measurements in nuclear pharmacies and clinics in the United States.

A blind performance test was conducted to evaluate dose-calibrator measurements at nuclear pharmacies in the United States (US). Two test-sample geometries were chosen to represent those used for measurements of 90Y-ibritumomab tiuxetan (ZEVALIN). The radioactivity concentration of test-samples was verified by the US National Institute of Standards and Technology. Forty-five results were reported by 10 participants. Eighty percent of reported values were within the US Pharmacopoeia content standard (+/-10%) for 90Y-ZEVALIN. All results were within US Nuclear Regulatory Commission conformance limits (+/-20%) for defining therapeutic misadministrations.

Influence of morbid obesity on the single-dose pharmacokinetics of daptomycin.

The present study characterized the single-dose pharmacokinetics of daptomycin dosed as 4 mg/kg of total body weight (TBW) in seven morbidly obese and seven age-, sex-, race-, and serum creatinine-matched healthy subjects. The glomerular filtration rate (GFR) was measured for both groups following a single bolus injection of [(125)I]sodium iothalamate. Noncompartmental analysis was used to determine the pharmacokinetic parameters, and these values were normalized against TBW, ideal body weight (IBW), and fat-free weight (FFW) for comparison of the two groups. All subjects enrolled in this study were female, and the mean (+/-standard deviation) body mass index was 46.2 +/- 5.5 kg/m(2) or 21.8 +/- 1.9 kg/m(2) for the morbidly obese or normal-weight group, respectively. The maximum plasma concentration and area under the concentration-time curve from dosing to 24 h were approximately 60% higher (P < 0.05) in the morbidly obese group than in the normal-weight group, and these were a function of the higher total dose received in the morbidly obese group. No differences in daptomycin volume of distribution (V), total clearance, renal clearance, or protein binding were noted between the two groups. Of TBW, FFW, or IBW, TBW provided the best correlation to V. In contrast, TBW overestimated GFR through creatinine clearance calculations using the Cockcroft-Gault equation. Use of IBW in the Cockcroft-Gault equation or use of the four-variable modification of diet in renal disease equation best estimated GFR in morbidly obese subjects. Further studies of daptomycin pharmacokinetics in morbidly obese patients with acute bacterial infections and impaired renal function are necessary to better predict appropriate dosage intervals.

Somatostatin-receptor-targeted alpha-emitting 213Bi is therapeutically more effective than beta(-)-emitting 177Lu in human pancreatic adenocarcinoma cells.

INTRODUCTION: Advance clinical cancer therapy studies of patients treated with somatostatin receptor (sstr)-targeted [DOTA(0)-Tyr(3)]octreotide (DOTATOC) labeled with low-linear-energy-transfer (LET) beta(-)-emitters have shown overall response rates in the range of 15-33%. In order to improve outcomes, we sought to compare the therapeutic effectiveness of sstr-targeted high-LET alpha-emitting (213)Bi to that of low-LET beta(-)-emitting (177)Lu by determining relative biological effectiveness (RBE) using the external gamma-beam of (137)Cs as reference radiation. METHODS: Sstr-expressing human pancreatic adenocarcinoma Capan-2 cells and A549 control cells were used for this study. The effects of different radiation doses of (213)Bi and (177)Lu labeled to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid and sstr-targeted DOTATOC were investigated with a clonogenic cell survival assay. Apoptosis was measured using the Cell Death Detection ELISA(PLUS) 10x kit. RESULTS: Using equimolar DOTATOC treatment with concurrent irradiation with a (137)Cs source as reference radiation, the calculated RBE of [(213)Bi]DOTATOC was 3.4, as compared to 1.0 for [(177)Lu]DOTATOC. As measured in terms of absorbance units, [(213)Bi]DOTATOC caused a 2.3-fold-greater release of apoptosis-specific mononucleosomes and oligonucleosomes than [(177)Lu]DOTATOC at the final treatment time of 96 h (P<.001) in sstr-expressing Capan-2 cells. CONCLUSIONS: In conclusion, at the same absorbed dose, [(213)Bi]DOTATOC is therapeutically more effective in decreasing survival than is [(177)Lu]DOTATOC in human pancreatic adenocarcinoma cells due to its comparatively higher RBE.

Linkage effects on binding affinity and activation of GPR30 and estrogen receptors ERalpha/beta with tridentate pyridin-2-yl hydrazine tricarbonyl-Re/(99m)Tc(I) chelates.

We describe a new structural class of neutral tridentate pyridin-2-yl hydrazine chelates for labeling with tricarbonyl Re/99mTc(I) under aqueous conditions and investigate the receptor binding of synthetic estradiol derivatives with the novel G-protein-coupled receptor GPR30 and estrogen receptors ERalpha/beta. The steroid linkage affected the affinity and selectivity of estrogen binding with these receptors. Fluorescence assays based on calcium signaling demonstrate that membrane-permeable chelates 2 and 3 interact with the receptors in whole cells. These results suggest that in vitro assays will facilitate the development of targeted imaging agents for intracellular receptors and the feasibility of targeting GPR30 and ERalpha/beta for diagnostic tumor imaging.

Characterization of a radiolabeled small molecule targeting leukocyte function-associated antigen-1 expression in lymphoma and leukemia.

OBJECTIVE: Leukocyte function-associated antigen-1 (LFA-1) is constitutively expressed on leukocytes, including overexpression on lymphomas and leukemias. We have developed a derivative of BIRT 377, an allosteric inhibitor of LFA-1, which may be chemically tagged without affecting binding. In this study, we modified this derivative, (R)-1-(4-aminobutyl)-5-(4-bromobenzyl)-3-(3,5-dichlorophenyl)-5-methylimidazolidine- 2,4-dione (butylamino-NorBIRT), and demonstrated its potential as a noninvasive imaging agent. METHODS: Specific binding of fluorescein-labeled butylamino-NorBIRT to both human and murine cells was demonstrated using equilibrium binding and dissociation techniques. A radiometal, lutetium-177 (Lu-177), was incorporated into the butylamino-NorBIRT through 1,4,7,10-tetraazacyclododecane-N,N',N",N'''- tetraacetic acid (DOTA) as a chelator. RESULTS: Equilibrium-binding experiments demonstrated that fluorescein- labeled butylamino-NorBIRT specifically binds human and murine LFA-1 with affinity constants of 135 and 186 nM, respectively. Dissociation kinetic experiments demonstrated an off-rate of 0.168/second(1) on murine cells, consistent with the observed affinity constant. Lutetium-177 was used for labeling, with > or =99.99% radiochemical purity and incorporation yield. This radiolabeled derivative exhibited high stability in fetal bovine serum (FBS) at 37 degrees C over 72 hours. (177)Lu-DOTA-butylamino-NorBIRT showed a binding affinity of 235 nM to human LFA-1 for equilibrium binding and competitive binding experiments. CONCLUSIONS: The radiolabeled DOTA-butylamino-NorBIRT may have potential as a noninvasive imaging or therapeutic agent in both human and mouse models.

213Bi-[DOTA0, Tyr3]octreotide peptide receptor radionuclide therapy of pancreatic tumors in a preclinical animal model.

PURPOSE: The somatostatin analogue [DOTA0, Tyr3]octreotide (DOTATOC) has previously been labeled with low linear energy transfer (LET) beta-emitters, such as 177Lu or 90Y, for tumor therapy. In this study, DOTATOC labeled with the high-LET alpha-emitter, 213Bi, was evaluated. EXPERIMENTAL DESIGN: The radiolabeling, stability, biodistribution, toxicity, safety, and therapeutic efficacy of 213Bi-DOTATOC (specific activity 7.4 MBq/microg) were investigated. Biodistribution studies to determine somatostatin receptor specificity were done in Lewis rats at 1 and 3 hours postinjection. Histopathology of various organs was used to evaluated toxicity and safety. Therapeutic efficacy of 4 to 22 MBq 213Bi-DOTATOC was determined in a rat pancreatic carcinoma model. RESULTS: Radiolabeling of the 213Bi-DOTATOC was achieved with radiochemical purity >95% and an incorporation yield > or = 99.9%. Biodistribution data showed specific binding to somatostatin receptor-expressing tissues. Administration of free 213Bi, compared with 213Bi-DOTATOC, resulted in higher radioactivity accumulation at 3 hours postinjection in the kidneys [34.47 +/- 1.40% injected dose/g (ID/g) tissue versus 11.15 +/- 0.46%, P < 0.0001] and bone marrow (0.31 +/- 0.01% ID/g versus 0.06 +/- 0.02%, P < 0.0324). A significant decrease in tumor growth rate was observed in rats treated with >11 MBq of 213Bi-DOTATOC 10 days postinjection compared with controls (P < 0.025). Treatment with >20 MBq of 213Bi-DOTATOC showed significantly greater tumor reduction when compared with animals receiving <11 MBq (P < 0.02). CONCLUSIONS: 213Bi-DOTATOC showed dose-related antitumor effects with minimal treatment-related organ toxicity. No acute or chronic hematologic toxicities were observed. Mild, acute nephrotoxicity was observed without evidence of chronic toxicity. 213Bi-DOTATOC is a promising therapeutic radiopharmaceutical for further evaluation.

Citrate synthase mutants of Agrobacterium are attenuated in virulence and display reduced vir gene induction.

A citrate synthase (CS) deletion mutant of Agrobacterium tumefaciens C58 is highly attenuated in virulence. The identity of the mutant was initially determined from its amino acid sequence, which is 68% identical to Escherichia coli and 77% identical to Brucella melitensis. The mutant lost all CS enzymatic activity, and a cloned CS gene complemented a CS mutation in Sinorhizobium. The CS mutation resulted in a 10-fold reduction in vir gene expression, which likely accounts for the attenuated virulence. When a plasmid containing a constitutive virG [virG(Con)] locus was introduced into this mutant, the level of vir gene induction was restored to nearly wild-type level. Further, the virG(Con)-complemented CS mutant strain induced tumors that were similar in size and number to those induced by the parental strain. The CS mutation resulted in only a minor reduction in growth rate in a glucose-salts medium. Both the CS mutant and the virG(Con)-complemented CS strain displayed similar growth deficiencies in a glucose-salts medium, indicating that the reduced growth rate of the CS mutant could not be responsible for the attenuated virulence. A search of the genome of A. tumefaciens C58 revealed four proteins, encoded on different replicons, with conserved CS motifs. However, only the locus that when mutated resulted in an attenuated phenotype has CS activity. Mutations in the other three loci did not result in attenuated virulence and any loss of CS activity, and none were able to complement the CS mutation in Sinorhizobium. The function of these loci remains unknown.

The intron 5/6 promoter region of the ship1 gene regulates expression in stem/progenitor cells of the mouse embryo.

The s-SHIP protein is a shorter isoform of the longer SHIP1 protein and lacks the N-terminal SH2 domain region contained in SHIP1. s-SHIP is expressed in ES cells and in enriched bone marrow stem cells, and may be controlled by a promoter within intron 5 of the ship1 gene. We therefore examined the potential specificity of promoter activity in ES cells of an intron 5/intron 6 ship1 genomic segment and its tissue specificity within transgenic mice expressing GFP from this promoter region. The results indicate that s-SHIP promoter activity is specific for ES cells in vitro and for known and presumptive stem/progenitor cells throughout embryo development of the transgenic mice. Specific GFP expression was observed in the blastocyst, primordial germ cells, thymus, arterioles, osteoblasts, and skin epidermis. The epidermis/epithelium is the progenitor for hair follicles, mammary tissue, and prostate. Interestingly, each of these latter tissues acquired a few GFP-positive cells in the course of their development from the epithelial layers, and these cells express marker proteins for stem/progenitor cells. These results identify potential stem cell populations, mark these cells for analyses in normal and cancer development, and implicate s-SHIP as an important protein in stem/progenitor cell function.

A comparison of high- versus low-linear energy transfer somatostatin receptor targeted radionuclide therapy in vitro.

INTRODUCTION: The somatostatin analog [DOTA(0)-Tyr(3)]-octreotide (DOTATOC) has been widely used to target somatostatin receptor expressing tumors for therapy using radionuclides such as (90)Y or (177)Lu. AIM: This aim of this study was to compare the effects of DOTATOC labeled to high linear energy transfer (LET) alpha-emitter (213)Bi and low-LET beta-emitter (177)Lu in vitro. MATERIALS AND METHODS: Somatostatin receptor (sstr)-positive cell line Capan-2 and sstr-negative control cell line A549 were used for the experiments. The effects of two exposure times using different radiation doses of high-LET alpha-emitter (213)Bi and low-LET beta-emitter (177)Lu were investigated using cell survival assay. The apoptotic effects were investigated using Cell Death Detection ELISA(PLUS)10x. The cumulated activity and the mean absorbed dose per unit cumulated activity were calculated using MIRD cellular Svalues. RESULTS: (213)Bi-DOTATOC had an approximately four times greater induction of apoptosis than (177)Lu-DOTATOC and a 100 times greater induction of apoptosis than nonradiolabeled DOTATOC. Nonspecific radiolabeled tetra-azacyclododecanetetra-acetic acid (DOTA) had a less pronounced effect on the cell survival and apoptosis, as compared to the sstr-specific radiolabeled DOTATOC. CONCLUSION: (213)Bi-DOTATOC is significantly more potent than (177)Lu-DOTATOC in vitro because of its high-LET alpha-emission.(213)Bi-DOTATOC shows enhanced effects on mitotic and apoptotic cell deaths.

The effect of selected preparation variables on the radiochemical purity of 99mTc-sestamibi.

OBJECTIVE: Measurement of cardiac perfusion via agents such as 99mTc-sestamibi (Cardiolite; DuPont-Merck Pharmaceutical Co., Inc.) is widely used in clinical nuclear medicine for the diagnosis of coronary artery disease. The monograph for 99mTc-sestamibi recommends at least 90% radiochemical purity (RCP) for clinical use. Various factors may influence the RCP of certain reagent kits. Some of these include the amount of activity added to the reagent kit, the generator ingrowth time, the generator manufacturer, the age of the eluate, and the age of the formulated kit. A D-optimal design with a 20-experiment run was devised to study the effects of these variables either alone or in combination on the RCP of 99mTc-sestamibi. METHODS: The RCP was assessed by Baker-Flex thin-layer and high-performance liquid chromatographic methods, immediately and 6 h after reconstitution of the 99mTc-sestamibi. RESULTS: The results showed that 4 of the 5 variables studied were statistically significant predictors of the RCP. The age of the formulated kit did not influence the RCP. CONCLUSION: For any combination of these 4 variables, the mean RCP remained greater than or equal to 90%, that is, within the recommended range of RCP for clinical use at radioactivity levels ranging from 5,550 MBq to 37,000 MBq.