Atorvastatin-loaded cubosome: a repurposed targeted delivery systems for enhanced targeting against breast cancer.

Cancer ranks as one of the most challenging illnesses to deal with because progressive phenotypic and genotypic alterations in cancer cells result in resistance and recurrence. Thus, the creation of novel medications or alternative therapy approaches is mandatory. Repurposing of old drugs is an attractive approach over the traditional drug discovery process in terms of shorter drug development duration, low-cost, highly efficient and minimum risk of failure. In this study Atorvastatin, a statin drug used to treat abnormal cholesterol levels and prevent cardiovascular disease in people at high risk, was introduced and encapsulated in cubic liquid crystals as anticancer candidate aiming at sustaining its release and achieving better cellular uptake in cancer cells. The cubic liquid crystals were successfully prepared and optimized with an entrapment effieciency of 73.57% ±1.35 and particle size around 200 nm. The selected formulae were effectively doped with radioactive iodine 131I to enable the noninvasive visualization and trafficking of the new formulae. The in vivo evaluation in solid tumor bearing mice was conducted for comparing131I-Atorvastatin solution,131I-Atorvastatin loaded cubosome and 131I-Atorvastatin chitosan coated cubosome. The in vivo biodistribution study revealed that tumor radioactivity uptake of 131I-Atorvastatin cubosome and chitosan coated cubosome exhibited high accumulation in tumor tissues (target organ) scoring ID%/g of 5.67 ± 0.2 and 5.03 ± 0.1, respectively 1h post injection compared to drug solution which recorded 3.09 ± 0.05% 1h post injection. Concerning the targeting efficiency, the target/non target ratio for 131I-Atorvastatin chitosan coated cubosome was higher than that of 131I-Atorvastatin solution and 131I ATV-loaded cubosome at all time intervals and recorded T/NT ratio of 2.908 2h post injection.

Synthesis and biological evaluation of [131I]iodocarvedilol as a potential radiopharmaceutical for heart imaging.

The optimization of the radiolabeling yield of carvedilol with iodine-131 was described. Dependence of the labeling yield of [131I]iodocarvedilol on the concentration of carvedilol, chloramine-T content, pH of the reaction mixture and reaction time was studied in details. Carvedilol was labeled with iodine-131 at pH 6 with a labeling yield of 92.6 ± 2.77% by using 100 µg carvedilol, 200 µg chloramin-T (CAT) and 30 min reaction time. The formed [131I]iodocarvedilol was nearly stable for a time up to one day. Biodistribution of [131I]iodocarvedilol was investigated in experimental animals. [131/123I]iodocarvedilol was located in the heart with a concentration of 19.6 ± 0.41% of the injected dose at 60 min post injection. It has a high heart uptake and heart to liver ratio, both of which are beneficial for high-quality SPECT (single-photon emission computerized tomography) myocardial imaging. [131/123I]iodocarvedilol solve most the drawbacks of the FDA (Food and Drug Administration) approved 99mTc-sestamibi.

Radio-iodination and biological evaluation of pentoxifylline as a novel probe for diagnosis of intermittent claudication.

The diagnosis of intermittent claudication (IC) is challenging. Imaging with radiopharmaceuticals provides a new method for detecting acute IC. Pentoxifylline improves blood flow to ischemic tissues via increasing erythrocyte elasticity and inhibiting platelet aggregation. Pentoxifylline was radio-iodinated with radioiodine-131 (131I) through a direct electrophilic substitution reaction. Furthermore, various factors that might influence the radiolabeling strategy were investigated. The radiochemical yield of [131I]iodopentoxiphyline was evaluated by using paper chromatography and HPLC methods. The biodistribution pattern of [131I]iodopentoxiphyline was studied, where Swiss albino mice was used as a model of acute limb ischemia-reperfusion. The maximum radiochemical yield of pentoxifylline was found to be 94.11 ± 2.35%. The biodistribution findings revealed that [131I]iodopentoxiphyline was significantly deposited at the ischemic site (left hind limbs), with encouraging target/non-target (T/NT) ratios. At 0.25 and 1 h post injection, the uptake of [131I]iodo-pentoxifylline was 5.30 ± 0.30 and 9.98 ± 1.12%, respectively. Also, the maximum T/NT ratio for [131I]iodo-pentoxifylline (9.45 ± 0.26) was obtained at 0.25 h post injection. Due to safety and selectivity, [131I]iodo-pentoxifylline may be a good prospective diagnostic tool for early identification of IC. Moreover, the outcome of this study can be expected to apply to I-123 as well.

Formulation of chitosan coated nanoliposomes for the oral delivery of colistin sulfate: in vitro characterization, 99mTc-radiolabeling and in vivo biodistribution studies.

Colistin sulfate is a very important antibiotic for the treatment of multidrug-resistant Gram-negative infections. Unfortunately, it has low oral bioavailability and several side effects following parenteral administration. The present study aims to develop chitosan-coated colistin nanoliposomes to improve the stability in the gastrointestinal tract and to enhance the oral delivery of colistin. The chitosan-coated colistin nanoliposomes were obtained via thin-film evaporation and electrostatic deposition methods using either Span 60, Tween 65 or Tween 80 as surfactants with different cholesterol: surfactant: soya lecithin ratios. The influence of systems variables was further characterized by vesicle size analysis, zeta potential (ZP), poly dispersibility index (PDI), and also their entrapment efficiency percentage (EE %) was evaluated. Various systems were formed with vesicle sizes in the nano-range, 155.64 ± 12.53 nm to 315.64 ± 15.90 nm, and EE % of 45.2 ± 2.9% to 81.8 ± 2.9%. Moreover, the ZP value of the prepared nanoliposomes switched from a negative to a positive value after chitosan coating. To track the released colistin in vivo, technetium 99m (99mTc) was incorporated into the optimum system (S-3) system via direct coupling with colistin. Chitosan-coated 99mTc-colistin nanoliposome, 99mTc-colistin suspension, and 99mTc-chitosan-coated nanoliposomes (placebo) were administered orally into bacterial infection (Escherichia coli) bearing mice. The biodistribution results showed that chitosan-coated nanoliposome significantly enhanced the bioavailability of colistin compared to colistin suspension (the commercially available). Moreover, the system effectively improved the localization of colistin at the infected muscle. In conclusion, this approach offers a promising tool for enhanced oral delivery of colistin.

Amelioration of Tumor Targeting and In Vivo Biodistribution of 99mTc-Methotrexate-Gold Nanoparticles (99mTc-Mex-AuNPs).

Gold nanoparticles (AuNPs) represent very attractive and promising drug delivery carriers due to their unique dimensions, adjustable surface functions, and controllable drug release. Therefore, AuNPs are used to overcome the limitations of conventional chemotherapy, for example methotrexate (Mex), one of the first-generation chemotherapy drugs for cancer treatment, whose usefulness has been restricted due to drug resistance and dose-dependent side effects. In the present study, the AuNPs drug delivery system was synthesized and loaded with technetium-99 m radiolabeled Methotrexate (99mTc-Mex) to produce new potential nanoradiopharmaceutical for tumor targeting and further imaging. The Methotrexate loaded gold nanoparticles (Mex-AuNPs) successfully prepared in small spherical particle size (20.3 nm), polydispersity index PDI (< 0.5) and a zeta potential (-17.6 mV) with loading efficiency% (93 ± 1.2%) of methotrexate at 30 min as an optimum stirring time and showed strong absorption peak for Mex-AuNPs at λmax, 525 nm. The in vitro release profile of Mex-AuNPs showed high release percent of methotrexate at pH 5; the Q0.5 h and Q8h were 21.2 ± 1.5% and 92.9 ± 3.4%, respectively. The in vitro cytotoxicity was investigated at different concentrations (0.024-50 µl/100 µl) of Mex-AuNPs (1 mg/ml) against MCF-7 (Michigan Cancer Foundation-7) breast cancer cells by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay technique. Mex-AuNPs showed higher anticancer activity with low inhibitory concentration (IC50 = 0.098 µl/100 µl) that was three times lower than the inhibitory concentration (IC50) of methotrexate (IC50 = 0.3 µl/100 µl). 99mTc-Mex complex prepared by direct reduction method at maximum radiochemical yield (RCY)% Ì´ 98.3 ± 1.09 % was loaded in AuNPs to form 99mTc-Mex-AuNPs with loading efficiency% (93 ± 1.2 %) at 30 min of stirring time. 99mTc-Mex-AuNPs showed convenient in vitro stability in mice serum up to 24 h with RCY% > 90 %. The preclinical biodistribution studies of 99mTc-Mex-AuNPs were performed in 3 experimental groups A (intravenous (I.V.) injected normal mice), B and C (I.V. and intratumor (I.T.) injected tumor bearing mice, respectively). The 99mTc-Mex-AuNPs achieved highest tumor uptake (93 ± 0.39 %ID/g) and highest Target/NonTarget (T/NT) ratio (58.1 ± 0.91) with high Tumor/Blood (T/B) ratio (25.8 ± 0.11) at 10 min post I.T. injection and retained high tumor uptake (79 ± 0.65 %ID/g) up to 60 min post I.T. injection before escaping into blood stream. Consequently, 99mTc-Mex-AuNPs can be considered as new potential nanoradiopharmaceutical in tumor diagnosis.

Miniaturized chromatographic systems for radiochemical purity evaluation of 131I-Ferulic acid as a new candidate in nuclear medicine applications.

Recently, the anticancer activity of ferulic acid (FA) which is a caffeic acid derivative has been reported. Therefore, in this study FA was radiocaped with 131I- to explore its potential as a tumor targeting agent. The radiolabeling process was carried out via electrophilic substitution reaction. The factors affecting labeling yield were optimized and the radiochemical purity (RCP) was assessed by various analytical techniques including paper chromatography (PC), thin layer chromatography (TLC), instant thin layer chromatography (ITLC), paper electrophoresis (PE) and high-performance liquid chromatography (HPLC). The RCP assay was extended to the utilization of miniaturized techniques including miniaturized PC (mini-PC), mini-TLC and mini-column chromatography (silica, sephadex-G25). Validation of mini-TLC, as one of 131I-FA RCP assay methods, was done according to ICH guidelines. Biodistribution studies of 131I-FA were performed on Ehrlich solid tumor bearing mice at various time points (5, 30, 60, 120 and 240 min), post injection. The radiolabeling yield of 131I-FA was 96.23 ± 0.45% and the miniaturized chromatographic systems showed high efficacy in RCP evaluation comparable to the conventional ones. Mini-TLC was proved to be specific, accurate, precise and linear. The tumor uptake of 131I-FA in solid tumor bearing mice was 4.35 ± 0.41 ID/g at 60 min with 2.79 as a tumor/muscle ratio. Consequently, 131I-FA could be used as a tumor targeting agent for nuclear medicine applications and the fast reaction monitoring could be achieved using miniaturized chromatographic techniques.

Outcome of Transcanalicular Endolaser and External Dacryocystorhinostomy in Chronic Dacryocystitis.

Nasolacrimal duct obstruction due to chronic dacryocystitis is the most common cause of epiphora. Dacryocystorhinostomy (DCR) is the treatment of choice for chronic dacryocystitis. This can be carried out by external, endoscopic and endolaser surgical approach. Though external DCR is still a gold standard and most popular method, the latest procedure of less traumatic DCR is transcanalicular approach. The study was done to evaluate the outcome of Transcanalicular Endolaser DCR regarding epiphora and surgery related complications by measuring anatomical success rate (patency assessed by irrigation), functional success rate (symptom free) and complication rate and to compare with External DCR (Ext-DCR). This prospective interventional study was conducted from October 2011 to September 2012 in Ophthalmology department of Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh. Total 62 patients included in the study as per inclusion and exclusion criteria of them 31 for TCEL-DCR and 31 for Ext-DCR. But during follow-up one patient was dropped from each group and finally outcome of 30 patients analyzed in each group. Mean age of the patients TCEL-DCR was 38.3±11.54 and of Ext-DCR was 38.4±14.01. In both groups females were the most sufferer (female: male = 1.5: 1). Functional and anatomical success rate of TCEL-DCR showed 93.3% and 83.3% after 3 months; 83.3% and 76.7% after 6 months respectively. Statistically non-significant difference was observed about success rate in comparison between groups. Per-operative complications were pain excessive bleeding. In TCEL-DCR pain complained 13.3% and excessive bleeding occurred in 3.3%. Where as in Ext-DCR pain complained 16.7% and excessive bleeding occurred in 20%; difference was statistically significant (p=0.001). Post-operative complications were bleeding and scar formation. Bleeding occurred in TCEL-DCR 6.67% and in Ext-DCR 10%. So, TCEL-DCR could be an alternative option for the treatment of chronic dacryocystitis especially for those patients who are conscious about scar formation and afraid about Ext-DCR technique.

I-131 doping of silver nanoparticles platform for tumor theranosis guided drug delivery.

Nanotechnology may be applied in medicine where the utilization of nanoparticles (≤100 nm) for the delivery and targeting of theranostic agents is at the forefront of projects in cancer nano-science. This study points a novel one step synthesis approach to build up polyethylene glycol capped silver nanoparticles doped with I-131 radionuclide (131I-doped Ag-PEG NPs). The formula was prepared with average hydrodynamic size 21 nm, zeta potential - 25 mV, radiolabeling yield 98 ±â€¯0.76%, and showed good in-vitro stability in saline and mice serum. The in-vitro cytotoxicity study of cold Ag-PEG NPs formula as a drug carrier vehicle showed no cytotoxic effect on normal cells (WI-38 cells) at a concentration below 3 µL/104 cells. The in-vivo biodistribution pattern of 131I-doped Ag-PEG NPs in solid tumor bearing mice showed high radioactivity accumulation in tumor tissues with maximum uptake of 35.43 ±â€¯1.12 and 63.8 ±â€¯1.3% ID/g at 60 and 15 min post intravenous (I.V.) and intratumoral injection (I.T.), respectively. Great potential of T/NT ratios were obtained throughout the experimental time points with maximum ratios 45.23 ±â€¯0.65 and 92.46 ±â€¯1.02 at 60 and 15 min post I.V. and I.T. injection, respectively. Thus, 131I-doped Ag-PEG NPs formulation could be displayed as a great potential tumor nano-sized theranostic probe.

Synthesis, characterization, radiolabeling and biodistribution of a novel cyclohexane dioxime derivative as a potential candidate for tumor imaging.

PURPOSE: Dioxime derivative is reported to exhibit high affinity towards tumor cells. The objective of the present study is to synthesize a new dioxime derivative to be labeled with technetium-99m for using as a solid tumor marker. MATERIALS AND METHODS: ((2E,2',3E,3')-3,3'-(cyclohexane-1,2-diylbis (azanylylidene)) bis-(butan-2-one)dioxime) was synthesized by condensation of Butan-2,3-dione monooxime and diaminocyclohexane and labeled with 99mTc. The in-vivo distribution of the agent was studied by carrying out biodistribution in tumor bearing Albino mice. RESULTS: A new cyclohexane dioxime derivative was synthesized with a good yield of 93 ± 2% and its complexation with 99mTc was prepared with 85 ± 4% radiochemical yield under the optimized conditions and the preparation exhibited in-vitro stability up to 6 h. Biodistribution studies showed high uptake in tumor cells with T/NT (target to non-target ratio) = 3.4 ± 0.2 after 0.5 h post injection. CONCLUSION: As a result of biodistribution studies, the newly synthesized cyclohexane dioxime derivative showed its good uptake in tumor cells, which affords a potential radiopharmaceutical that could be used as a good tumor imaging agent.

131I-trazodone: preparation, quality control and in vivo biodistribution study by intranasal and intravenous routes as a hopeful brain imaging radiopharmaceutical.

OBJECTIVES: The preparation of 131I-trazodone hydrochloride and its biological evaluation as a promising brain imaging radiopharmaceutical using two routes of administration. MATERIAL AND METHODS: Trazodone (TZ) was radiolabelled with 131I using direct electrophilic substitution, and different factors affecting labelling yield were studied. Quality control of 131I-TZ was carried out using ascending paper chromatography, paper electrophoresis, and high pressure liquid chromatography (HPLC). In vivo biodistribution of 131I-TZ was evaluated in Swiss albino mice using 3 methods: intravenous 131I-TZ solution (IVS), intranasal 131I-TZ solution (INS), and intranasal 131I-TZ microemulsion (INME). RESULTS: Optimum labelling yield of 91.23±2.12% was obtained with in vitro stability of 131I-TZ up to 6h at room temperature. The biodistribution results showed a notably higher and sustained brain uptake for INME compared to IVS and INS at all time intervals. In addition, heart and blood uptake levels for INME were lower than those for IV solution which, in turn, could decrease the systemic side effects of trazodone. Also, the 131I-trazodone INME brain uptake of 6.7±0.5%ID/g was higher than that of 99mTc-ECD and 99mTc-HMPAO (radiopharmaceuticals currently used for brain imaging). CONCLUSION: 131/123I-trazodone formulated as INME could be used as a promising radiopharmaceutical for brain imaging.

Borrelia burgdorferi CheY2 Is Dispensable for Chemotaxis or Motility but Crucial for the Infectious Life Cycle of the Spirochete.

The requirements for bacterial chemotaxis and motility range from dispensable to crucial for host colonization. Even though more than 50% of all sequenced prokaryotic genomes possess at least one chemotaxis signaling system, many of those genomes contain multiple copies of a chemotaxis gene. However, the functions of most of those additional genes are unknown. Most motile bacteria possess at least one CheY response regulator that is typically dedicated to the control of motility and which is usually essential for virulence. Borrelia burgdorferi appears to be notably different, in that it has three cheY genes, and our current studies on cheY2 suggests that it has varied effects on different aspects of the natural infection cycle. Mutants deficient in this protein exhibit normal motility and chemotaxis in vitro but show reduced virulence in mice. Specifically, the cheY2 mutants were severely attenuated in murine infection and dissemination to distant tissues after needle inoculation. Moreover, while ΔcheY2 spirochetes are able to survive normally in the Ixodes ticks, mice fed upon by the ΔcheY2-infected ticks did not develop a persistent infection in the murine host. Our data suggest that CheY2, despite resembling a typical response regulator, functions distinctively from most other chemotaxis CheY proteins. We propose that CheY2 serves as a regulator for a B. burgdorferi virulence determinant that is required for productive infection within vertebrate, but not tick, hosts.

Synthesis of (125) I-lamivudine and (125) I-lamivudine-ursodeoxycholic acid codrug.

The preparation of (125) I-lamivudine ((125) I-3TC) and (125) I-lamivudine-ursodeoxycholic acid codrug ((125) I-3TC-UDCA), suitable for comparative biodistribution studies, is described. The synthesis of the unlabeled precursor 3TC-UDCA proceeds in an 11.6% yield, and the radiolabelling yields for (125) I-3TC and (125) I-3TC-UDCA were 89 and 92%, respectively. The final products are radiochemically pure (greater than 98%).

Associations and Risk Factors of Diabetic Maculopathy.

Diabetic maculopathy is characterised by increased capillary leakage in the main retinal vessels and by alterations in the microcirculation of the macula. Maculopathy occurs frequently in type 1 and type 2 diabetic patients. Prevalence is higher in type 2 than in type 1 diabetic patients. Factors associated with the development of maculopathy are mostly unknown. As maculopathy is the main cause of vision deprivation in diabetic patients it is essential to know the associations and risk factors of diabetic maculopathy so that appropriate measures can be taken to prevent as well as treat diabetic maculopathy. We started the research work to find out the relation between diabetic maculopathy and various associated factors and risk factors for patients with diabetic retinopathy with maculopathy. This cross-sectional observational study done at the Department of Ophthalmology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka & National Institute of Ophthalmology & Hospital (NIO & H), Sher-e-Bangla Nagar, Dhaka, Bangladesh from January 2006 to June 2006. In this study out of 50 patients, diabetes was controlled in 20(40%) patients and uncontrolled in 30(60%). A significant percentage of patients (40%) had elevated blood pressure. Diabetic autonomic neuropathy was observed in 24% cases and polyneuropathy was observed in 36% cases. It is evident that diabetic maculopathy has association with dyslipidaemia, abnormal renal function due to nephropathy. This study lighted on the association of diabetic maculopathy with diabetic nephropathy, cardiac abnormalities and diabetic neuropathy.

An easy and effective method for synthesis and radiolabelling of risedronate as a model for bone imaging.

This study aimed to provide an easy method for synthesis of 1-hydroxy-2-(3-pyridyl) ethylidene bisphosphonic acid monosodium (sod. risedronate) with a high yield of 71%. The synthesized risedronate was labeled with technetium-99 m using two different reducing agents (SnCl2 .2H2 O and NaBH4 ) where NaBH4 gave stable complex and higher radiochemical yield more than SnCl2 .2H2 O. The results showed that, the radiochemical purity of (99m) Tc(NaBH4 )-risedronate was 99.2 ± 0.6% and its stability was up to 6 h. Biodistribution study showed high uptake and long retention of (99m) Tc(NaBH4 )-risedronate in bone starting from 15 min (29 ± 2.5% ID/organ) up to 4 h (35.1 ± 3.2 ID/organ) post injection. This research could introduce an easy and effective method for synthesis and labeling of risedrionate and affording a good tracer for bone imaging.

Borrelia burgdorferi CheD Promotes Various Functions in Chemotaxis and the Pathogenic Life Cycle of the Spirochete.

Borrelia burgdorferi possesses a sophisticated chemotaxis signaling system; however, the roles of the majority of the chemotaxis proteins in the infectious life cycle have not yet been demonstrated. Specifically, the role of CheD during host colonization has not been demonstrated in any bacterium. Here, we systematically characterized the B. burgdorferi CheD homolog using genetics and biochemical and mouse-tick-mouse infection cycle studies. Bacillus subtilis CheD plays an important role in chemotaxis by deamidation of methyl-accepting chemotaxis protein receptors (MCPs) and by increasing the receptor kinase activity or enhancing CheC phosphatase activity, thereby regulating the levels of the CheY response regulator. Our biochemical analysis indicates that B. burgdorferi CheD significantly enhances CheX phosphatase activity by specifically interacting with the phosphatase. Moreover, CheD specifically binds two of the six MCPs, indicating that CheD may also modulate the receptor proteins. Although the motility of the cheD mutant cells was indistinguishable from that of the wild-type cells, the mutant did exhibit reduced chemotaxis. Importantly, the mutant showed significantly reduced infectivity in C3H/HeN mice via needle inoculation. Mouse-tick-mouse infection assays indicated that CheD is dispensable for acquisition or transmission of spirochetes; however, the viability of cheD mutants in ticks is marginally reduced compared to that of the wild-type or complemented cheD spirochetes. These data suggest that CheD plays an important role in the chemotaxis and pathogenesis of B. burgdorferi We propose potential connections between CheD, CheX, and MCPs and discuss how these interactions play critical roles during the infectious life cycle of the spirochete.

Preparation and biological evaluation of (99m)Tc-ropinirole as a novel radiopharmaceutical for brain imaging.

Noninvasive brain imaging is a process that allows scientists and physicians to view and monitor the areas of the brain. The aim of this study was to formulate a novel radiopharmaceutical for the detection of brain disorders at early stages in susceptible patients. (99m) Tc-ropinirole was prepared by the direct complexation of ropinirole with technetium-99m. The results showed that the radiochemical yield (99m) Tc-ropinirole was 92 ± 2.87% and the radiochemical yield was evaluated by paper chromatography and HPLC. In vitro studies showed that the formed complex was stable for up to 6 h. In vivo uptake of (99m) Tc-ropinirole in the brain was 4.87 ± 0.15% injected dose/g organ at 30 min post-injection, which cleared from the brain with time till it reaches 2.3% at 2 h post-injection indicating that the brain uptake of (99m) Tc-ropinirole is higher than that of the commercially available (99m) Tc-HMPAO, which is 2.25% at 30 min. Pre-dosing mice with cold ropinirole reduced the brain uptake to 0.26 ± 0.01% injected dose/g organ, so this confirms the high specificity and selectivity of this radiotracer for the assessment of the dopamine receptors.

Motor rotation is essential for the formation of the periplasmic flagellar ribbon, cellular morphology, and Borrelia burgdorferi persistence within Ixodes scapularis tick and murine hosts.

Borrelia burgdorferi must migrate within and between its arthropod and mammalian hosts in order to complete its natural enzootic cycle. During tick feeding, the spirochete transmits from the tick to the host dermis, eventually colonizing and persisting within multiple, distant tissues. This dissemination modality suggests that flagellar motor rotation and, by extension, motility are crucial for infection. We recently reported that a nonmotile flaB mutant that lacks periplasmic flagella is rod shaped and unable to infect mice by needle or tick bite. However, those studies could not differentiate whether motor rotation or merely the possession of the periplasmic flagella was crucial for cellular morphology and host persistence. Here, we constructed and characterized a motB mutant that is nonmotile but retains its periplasmic flagella. Even though ΔmotB bacteria assembled flagella, part of the mutant cell is rod shaped. Cryoelectron tomography revealed that the flagellar ribbons are distorted in the mutant cells, indicating that motor rotation is essential for spirochetal flat-wave morphology. The ΔmotB cells are unable to infect mice, survive in the vector, or migrate out of the tick. Coinfection studies determined that the presence of these nonmotile ΔmotB cells has no effect on the clearance of wild-type spirochetes during murine infection and vice versa. Together, our data demonstrate that while flagellar motor rotation is necessary for spirochetal morphology and motility, the periplasmic flagella display no additional properties related to immune clearance and persistence within relevant hosts.

Radioiodinated acebutolol as a new highly selective radiotracer for myocardial perfusion imaging.

Acebutolol was successfully labeled with (125) I via direct electrophilic substitution reaction. Radioiodinated acebutolol was prepared with a maximum radiochemical yield of 96.5 ± 0.3% and in vitro stability up to 72 h. The in vivo biological distribution of radioiodinated acebutolol showed high heart uptake of 37.8 ± 0.14% injected activity/g organ with low lungs and liver uptakes at 5 min post-injection. In vivo receptor blocking study was carried out in mice to evaluate its selectivity to heart. Radioiodinated acebutolol showed fast heart accumulation with high heart/liver ratio, which provides the ability for fast myocardial imaging with significant decrease in the radiation hazards risk on patients. So, radioiodinated acebutolol could be displayed as a radiotracer drug of choice in case of emergency patients for myocardial perfusion imaging.

Biodistribution of 99mTc-sunitinib as a potential radiotracer for tumor hypoxia imaging.

Tyrosine kinases are groups of enzymes, which are over-expressed in solid tumor cells, representing good targets for different drugs such as sunitinib (N-[2-(diethylamino)ethyl]-5-{[(3Z)-5-fluoro-2-oxo-2,3-dihydro-1H-indol-3-ylidene]methyl}-2,4-dimethyl-1H-pyrrole-3-carboxamide). The aim of this work was to design and synthesize (99m)Tc-sunitinib radiotracer and to study its tumor binding specificity as a novel selective radiopharmaceutical for tumor hypoxia imaging. The in vivo biodistribution of (99m)Tc-sunitinib in tumor bearing mice showed high target/non-target (T/NT) ratio (T/NT ~ 3 at 60 min post injection). This preclinical high biological accumulation in tumor cells suggests that (99m)Tc-sunitinib is ready to go through the clinical trials as a potential selective radiotracer able to image tumor hypoxia.

Cryoelectron tomography reveals the sequential assembly of bacterial flagella in Borrelia burgdorferi.

Periplasmic flagella are essential for the distinctive morphology, motility, and infectious life cycle of the Lyme disease spirochete Borrelia burgdorferi. In this study, we genetically trapped intermediates in flagellar assembly and determined the 3D structures of the intermediates to 4-nm resolution by cryoelectron tomography. We provide structural evidence that secretion of rod substrates triggers remodeling of the central channel in the flagellar secretion apparatus from a closed to an open conformation. This open channel then serves as both a gateway and a template for flagellar rod assembly. The individual proteins assemble sequentially to form a modular rod. The hook cap initiates hook assembly on completion of the rod, and the filament cap facilitates filament assembly after formation of the mature hook. Cryoelectron tomography and mutational analysis thus combine synergistically to provide a unique structural blueprint of the assembly process of this intricate molecular machine in intact cells.