A dual-luciferase bioluminescence system for the assessment of cellular therapies

Bioluminescence imaging is a well-established platform for evaluating engineered cell therapies in preclinical studies. However, despite the discovery of new luciferases and substrates, optimal combinations to simultaneously monitor two cell populations remain limited. This makes the functional assessment of cellular therapies cumbersome and expensive, especially in preclinical in vivo models. In this study, we explored the potential of using a green bioluminescence-emitting click beetle luciferase, CBG99, and a red bioluminescence-emitting firefly luciferase mutant, Akaluc, together to simultaneously monitor two cell populations. Using various chimeric antigen receptor T cells and tumor pairings, we demonstrate that these luciferases are suitable for real-time tracking of two cell types using 2D and 3D cultures in vitro and experimental models in vivo. Our data show the broad compatibility of this dual-luciferase (duo-luc) system with multiple bioluminescence detection equipment ranging from benchtop spectrophotometers to live animal imaging systems. Although this study focused on investigating complex CAR T cells and tumor cell interactions, this duo-luc system has potential utility for the simultaneous monitoring of any two cellular components-for example, to unravel the impact of a specific genetic variant on clonal dominance in a mixed population of tumor cells.

Engineering CD276/B7-H3-targeted antibody-drug conjugates with enhanced cancer-eradicating capability

CD276/B7-H3 represents a promising target for cancer therapy based on widespread overexpression in both cancer cells and tumor-associated stroma. In previous preclinical studies, CD276 antibody-drug conjugates (ADCs) exploiting a talirine-type pyrrolobenzodiazepine (PBD) payload showed potent activity against various solid tumors but with a narrow therapeutic index and dosing regimen higher than that tolerated in clinical trials using other antibody-talirine conjugates. Here, we describe the development of a modified talirine PBD-based fully human CD276 ADC, called m276-SL-PBD, that is cross-species (human/mouse) reactive and can eradicate large 500-1,000-mm3 triple-negative breast cancer xenografts at doses 10- to 40-fold lower than the maximum tolerated dose. By combining CD276 targeting with judicious genetic and chemical ADC engineering, improved ADC purification, and payload sensitivity screening, these studies demonstrate that the therapeutic index of ADCs can be substantially increased, providing an advanced ADC development platform for potent and selective targeting of multiple solid tumor types.

Cross-neutralizing protection of vaginal and oral mucosa from HPV challenge by vaccination in a mouse model

The species and tissue specificities of HPV (human papillomavirus) for human infection and disease complicates the process of prophylactic vaccine development in animal models. HPV pseudoviruses (PsV) that carry only a reporter plasmid have been utilized in vivo to demonstrate cell internalization in mouse mucosal epithelium. The current study sought to expand the application of this HPV PsV challenge model with both oral and vaginal inoculation and to demonstrate its utility for testing vaccine-mediated dual-site immune protection against several HPV PsV types. We observed that passive transfer of sera from mice vaccinated with the novel experimental HPV prophylactic vaccine RG1-VLPs (virus-like particles) conferred HPV16-neutralizing as well as cross-neutralizing Abs against HPV39 in naïve recipient mice. Moreover, active vaccination with RG1-VLPs also conferred protection to challenge with either HPV16 or HPV39 PsVs at both vaginal and oral sites of mucosal inoculation. These data support the use of the HPV PsV challenge model as suitable for testing against diverse HPV types at two sites of challenge (vaginal vault and oral cavity) associated with the origin of the most common HPV-associated cancers, cervical cancer and oropharyngeal cancer.

Method To Diversify Cyanine Chromophore Functionality Enables Improved Biomolecule Tracking and Intracellular Imaging

Heptamethine indocyanines are invaluable probes for near-infrared (NIR) imaging. Despite broad use, there are only a few synthetic methods to assemble these molecules, and each has significant limitations. Here, we report the use of pyridinium benzoxazole (PyBox) salts as heptamethine indocyanine precursors. This method is high yielding, simple to implement, and provides access to previously unknown chromophore functionality. We applied this method to create molecules to address two outstanding objectives in NIR fluorescence imaging. First, we used an iterative approach to develop molecules for protein-targeted tumor imaging. When compared to common NIR fluorophores, the optimized probe increases the tumor specificity of monoclonal antibody (mAb) and nanobody conjugates. Second, we developed cyclizing heptamethine indocyanines with the goal of improving cellular uptake and fluorogenic properties. By modifying both the electrophilic and nucleophilic components, we demonstrate that the solvent sensitivity of the ring-open/ring-closed equilibrium can be modified over a wide range. We then show that a chloroalkane derivative of a compound with tuned cyclization properties undergoes particularly efficient no-wash live cell imaging using organelle-targeted HaloTag self-labeling proteins. Overall, the chemistry reported here broadens the scope of accessible chromophore functionality, and, in turn, enables the discovery of NIR probes with promising properties for advanced imaging applications.

Doubly Strapped Zwitterionic NIR-I and NIR-II Heptamethine Cyanine Dyes for Bioconjugation and Fluorescence Imaging

Heptamethine cyanine dyes enable deep tissue fluorescence imaging in the near infrared (NIR) window. Small molecule conjugates of the benchmark dye ZW800-1 have been tested in humans. However, long-term imaging protocols using ZW800-1 conjugates are limited by their instability, primarily because the chemically labile C4'-O-aryl linker is susceptible to cleavage by biological nucleophiles. Here, we report a modular synthetic method that produces novel doubly strapped zwitterionic heptamethine cyanine dyes, including a structural analogue of ZW800-1, with greatly enhanced dye stability. NIR-I and NIR-II versions of these doubly strapped dyes can be conjugated to proteins, including monoclonal antibodies, without causing undesired fluorophore degradation or dye stacking on the protein surface. The fluorescent antibody conjugates show excellent tumor-targeting specificity in a xenograft mouse tumor model. The enhanced stability provided by doubly strapped molecular design will enable new classes of in vivo NIR fluorescence imaging experiments with possible translation to humans.

Modified norcyanines enable ratiometric pH imaging beyond 1000 nm

Activatable fluorophores with emission beyond 1000 nm have the potential to enable high contrast imaging in complex in vivo settings. However, there are few scaffolds that can be applied to this challenge. Here we detail the synthesis and evaluation of benzo[c,d]indole-substituted norcyanines that enable pH responsive fluorescence imaging in the long wavelength (>1150 nm) range. A key component of our molecular design is the installation of a hydrophilic substituted quaternary amine in the central dihydropyridine ring system. A compound with a C4'-phenyl substituent, but not the C4'-protio homologue, exhibits absorbance maxima of 740 nm and 1130 nm in basic and acidic media, respectively, with evidence of J-aggregate-like properties. These two distinct absorbances enabled ratiometric imaging of probe internalization in a tumor model. Overall, these studies provide a new class of activatable long-wavelength responsive fluorophores with promising photophysical properties.

Palm cooling temperatures on thermal, physiological, perceptual, and ergogenic indices from rowing workouts in a thermoneutral environment

Gel pack temperatures were compared for responses to thermal, physiological, perceptual, and ergogenic indices from healthy women (n = 12) and men (n = 8). They did three rowing workouts to identify an ideal temperature. In a randomised sequence, and as subjects wore gloves equipped with mesh pouches during workouts, gel packs at one of the three average temperatures (10.6, 12.6, or 14.9°C) were inserted into the pouches. Data were collected before, during and after multi-stage workouts. Thermal, physiological, and perceptual data were each compared with three-factor (condition, gender, time) mixed effect model ANCOVAs, with repeated measures for condition and time, and gender as a between subjects' factor. Distance rowed was assessed with two-factor (condition, gender) mixed effect model ANCOVAs, with repeated measures for condition, and gender as a between subjects' factor. Within-subject contrasts was the post-hoc, and α = 0.05 denoted significance. Despite small differences for distance rowed, many dependent variables had significant inter-condition effects, whereby 10.6°C gel packs had the best thermal and physiological responses. The 10.6°C temperature 1): likely removed the most body heat, perhaps through cold-induced vasodilation and, 2): may be optimal, as it evoked the best thermal and physiological responses.

Cyanine Masking: A Strategy to Test Functional Group Effects on Antibody Conjugate Targeting

Conjugates of small molecules and antibodies are broadly employed diagnostic and therapeutic agents. Appending a small molecule to an antibody often significantly impacts the properties of the resulting conjugate. Here, we detail a systematic study investigating the effect of various functional groups on the properties of antibody-fluorophore conjugates. This was done through the preparation and analysis of a series of masked heptamethine cyanines (CyMasks)-bearing amides with varied functional groups. These were designed to exhibit a broad range of physical properties, and include hydrophobic (-NMe2), pegylated (NH-PEG-8 or NH-PEG-24), cationic (NH-(CH2)2NMe3+), anionic (NH-(CH2)2SO3-), and zwitterionic (N-(CH2)2NMe3+)-(CH2)3SO3-) variants. The CyMask series was appended to monoclonal antibodies (mAbs) and analyzed for the effects on tumor targeting, clearance, and non-specific organ uptake. Among the series, zwitterionic and pegylated dye conjugates had the highest tumor-to-background ratio (TBR) and a low liver-to-background ratio. By contrast, the cationic and zwitterionic probes had high tumor signal and high TBR, although the latter also exhibited an elevated liver-to-background ratio (LBR). Overall, these studies provide a strategy to test the functional group effects and suggest that zwitterionic substituents possess an optimal combination of high tumor signal, TBR, and low LBR. These results suggest an appealing strategy to mask hydrophobic payloads, with the potential to improve the properties of bioconjugates in vivo.

Targeted Fluorogenic Cyanine Carbamates Enable In Vivo Analysis of Antibody-Drug Conjugate Linker Chemistry

Antibody-drug conjugates (ADCs) are a rapidly emerging therapeutic platform. The chemical linker between the antibody and the drug payload plays an essential role in the efficacy and tolerability of these agents. New methods that quantitatively assess the cleavage efficiency in complex tissue settings could provide valuable insights into the ADC design process. Here we report the development of a near-infrared (NIR) optical imaging approach that measures the site and extent of linker cleavage in mouse models. This approach is enabled by a superior variant of our recently devised cyanine carbamate (CyBam) platform. We identify a novel tertiary amine-containing norcyanine, the product of CyBam cleavage, that exhibits a dramatically increased cellular signal due to an improved cellular permeability and lysosomal accumulation. The resulting cyanine lysosome-targeting carbamates (CyLBams) are ∼50× brighter in cells, and we find this strategy is essential for high-contrast in vivo targeted imaging. Finally, we compare a panel of several common ADC linkers across two antibodies and tumor models. These studies indicate that cathepsin-cleavable linkers provide dramatically higher tumor activation relative to hindered or nonhindered disulfides, an observation that is only apparent with in vivo imaging. This strategy enables quantitative comparisons of cleavable linker chemistries in complex tissue settings with implications across the drug delivery landscape.

Surface-fill hydrogel attenuates the oncogenic signature of complex anatomical surface cancer in a single application

Tumours growing in a sheet-like manner on the surface of organs and tissues with complex topologies represent a difficult-to-treat clinical scenario. Their complete surgical resection is difficult due to the complicated anatomy of the diseased tissue. Residual cancer often responds poorly to systemic therapy and locoregional treatment is hindered by the limited accessibility to microscopic tumour foci. Here we engineered a peptide-based surface-fill hydrogel (SFH) that can be syringe- or spray-delivered to surface cancers during surgery or used as a primary therapy. Once applied, SFH can shape change in response to alterations in tissue morphology that may occur during surgery. Implanted SFH releases nanoparticles composed of microRNA and intrinsically disordered peptides that enter cancer cells attenuating their oncogenic signature. With a single application, SFH shows efficacy in four preclinical models of mesothelioma, demonstrating the therapeutic impact of the local application of tumour-specific microRNA, which might change the treatment paradigm for mesothelioma and possibly other surface cancers.

Antibacterial Gel Coatings Inspired by the Cryptic Function of a Mussel Byssal Peptide

Although the adhesive and cohesive nature of mussel byssal proteins have long served to inspire the design of materials embodying these properties, their characteristic amino acid compositions suggest that they might also serve to inspire an unrelated material function not yet associated with this class of protein. Herein, it is demonstrated that a peptide derived from mussel foot protein-5, a key protein in mussel adhesion, displays antibacterial properties, a yet unreported activity. This cryptic function serves as inspiration for the design of a new class of peptide-based antibacterial adhesive hydrogels prepared via self-assembly, which are active against drug-resistant Gram-positive bacteria. The gels exert two mechanisms of action, surface-contact membrane disruption and oxidative killing affected by material-produced H₂ O₂ . Detailed studies relating amino acid composition and sequence to material mechanical adhesion/cohesion and antibacterial activity affords the MIKA2 adhesive gel, a material with a superior activity that is shown to inhibit colonization of titanium implants in mice.

Abstract 3007: Imaging characterization of NCI patient derived model repository (PDMR) xenografts

The purpose of this work is to provide imaging data on patient derived xenografts models that are available from the National Cancer Institute Patient-Derived Models Repository (https://pdmr.cancer.gov) that may be useful to investigators in deciding which models to use in testing therapeutics or designing co-clinical trials. Using imaging to monitor progress of a treatment or evaluate development or prevention of metastases has advantages in minimizing the number of mice required as well as providing more information about metabolic status and tumor heterogeneity.

NSG mice were implanted with each model and monitored with non-invasive imaging. The core imaging methodologies were T2W magnetic resonance imaging (MRI), to visualize heterogeneity and determine the usefulness of MRI to detect metastatic disease; 18F fluorodeoxyglucose PET/CT, to evaluate aerobic glycolysis; and 3'-Deoxy-3'-(18)F-fluorothymidine PET/CT, to evaluate proliferation. This work is ongoing and to date we have performed MRI on over 80 models with diverse tumor histology with a subset also undergoing FDG PET (77 models) and FLT PET (36 models).

These models and their imaging characteristics will be presented. Nineteen models have demonstrated metastatic disease that could be detected by non-contrast MRI imaging with pathological confirmation, including ones derived from melanoma, lung, colon, pancreatic, uterine, anal, and head & neck. Four of these (two colon adenocarcinoma, one melanoma and one pancreatic adenocarcinoma) have undergone more extensive characterization evaluating cohorts to determine location, timing of appearance, and penetrance of metastasis. These experiments evaluated cohorts of animals who were monitored as the primary tumors grew and others for whom the primary tumor was excised to encourage metastatic spread. The results of this metastatic characterization will be summarized. Additionally, the image data and the appropriate Standard Operating Procedures (SOP's) will be posted in The Cancer Imagining Archive (TCIA) https://www.cancerimagingarchive.net/ for investigators to access. The goal of this poster is to make investigators aware of the availability of this complementary imaging data as they consider research on models accessible from the NCI PDMR.

Citation Format: Paula M. Jacobs, James L. Tatum, Joseph D. Kalen, Lilia V. Ileva, Lisa A. Riffle, Keita Saito, Nimit L. Patel, Jessica Phillips, Melinda Hollingshead, Yvonne A. Evrard, Michelle Gottholm-Ahalt, Chelsea Sanders, Amy James, Simone Difilippantonio, Elijah F. Edmondson, James H. Doroshow. Imaging characterization of NCI patient derived model repository (PDMR) xenografts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3007.

Studying Triple Negative Breast Cancer Using Orthotopic Breast Cancer Model

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype with limited therapeutic options. When compared to patients with less aggressive breast tumors, the 5-year survival rate of TNBC patients is 77% due to their characteristic drug-resistant phenotype and metastatic burden. Toward this end, murine models have been established aimed at identifying novel therapeutic strategies limiting TNBC tumor growth and metastatic spread. This work describes a practical guide for the TNBC orthotopic model where MDA-MB-231 breast cancer cells suspended in a basement membrane matrix are implanted in the fourth mammary fat pad, which closely mimics the cancer cell behavior in humans. Measurement of tumors by caliper, lung metastasis assessment via in vivo and ex vivo imaging, and molecular detection are discussed. This model provides an excellent platform to study therapeutic efficacy and is especially suitable for the study of the interaction between the primary tumor and distal metastatic sites.

Melanoblast transcriptome analysis reveals pathways promoting melanoma metastasis

Cutaneous malignant melanoma is an aggressive cancer of melanocytes with a strong propensity to metastasize. We posit that melanoma cells acquire metastatic capability by adopting an embryonic-like phenotype, and that a lineage approach would uncover metastatic melanoma biology. Using a genetically engineered mouse model to generate a rich melanoblast transcriptome dataset, we identify melanoblast-specific genes whose expression contribute to metastatic competence and derive a 43-gene signature that predicts patient survival. We identify a melanoblast gene, KDELR3, whose loss impairs experimental metastasis. In contrast, KDELR1 deficiency enhances metastasis, providing the first example of different disease etiologies within the KDELR-family of retrograde transporters. We show that KDELR3 regulates the metastasis suppressor, KAI1, and report an interaction with the E3 ubiquitin-protein ligase gp78, a regulator of KAI1 degradation. Our work demonstrates that the melanoblast transcriptome can be mined to uncover targetable pathways for melanoma therapy.

A Nonaggregating Heptamethine Cyanine for Building Brighter Labeled Biomolecules

Heptamethine cyanines are broadly used for a range of near-infrared imaging applications. As with many fluorophores, these molecules are prone to forming nonemissive aggregates upon biomolecule conjugation. Prior work has focused on persulfonation strategies, which only partially address these issues. Here, we report a new set of peripheral substituents, short polyethylene glycol chains on the indolenine nitrogens and a substituted alkyl ether at the C4′ position, that provide exceptionally aggregation-resistant fluorophores. These symmetrical molecules are net-neutral, can be prepared in a concise sequence, and exhibit no evidence of H-aggregation even at high labeling density when appended to monoclonal antibodies or virus-like particles. The resulting fluorophore–biomolecule conjugates exhibit exceptionally bright in vitro and in vivo signals when compared to a conventional persulfonated heptamethine cyanine. Overall, these efforts provide a new class of heptamethine cyanines with significant utility for complex labeling applications.

COX-2 inhibition potentiates antiangiogenic cancer therapy and prevents metastasis in preclinical models

Antiangiogenic agents that block vascular endothelial growth factor (VEGF) signaling are important components of current cancer treatment modalities but are limited by alternative ill-defined angiogenesis mechanisms that allow persistent tumor vascularization in the face of continued VEGF pathway blockade. We identified prostaglandin E2 (PGE2) as a soluble tumor-derived angiogenic factor associated with VEGF-independent angiogenesis. PGE2 production in preclinical breast and colon cancer models was tightly controlled by cyclooxygenase-2 (COX-2) expression, and COX-2 inhibition augmented VEGF pathway blockade to suppress angiogenesis and tumor growth, prevent metastasis, and increase overall survival. These results demonstrate the importance of the COX-2/PGE2 pathway in mediating resistance to VEGF pathway blockade and could aid in the rapid development of more efficacious anticancer therapies.

Cardioprotective effect of Saraca indica against cyclophosphamide induced cardiotoxicity in rats: a biochemical, electrocardiographic and histopathological study

Objectives:

Cardioprotective activity of alcoholic extract of Saraca indica (SI) bark was investigated against cyclophosphamide induced cardiotoxicity.

Materials and Methods:

Cardiotoxicity was induced in Wistar rats by administering cyclophosphamide (200 mg/kg, i.p.) single injection on first day of experimental period. Saraca indica (200 and 400 mg/kg, p.o.) was administered immediately after administration of cyclophosphamide on first day and daily for 10 days. The general observations and mortality were measured.

Results:

Cyclophosphamide administration significantly (p < 0.05) increased lipid peroxidation (LPO) and decreased the levels of antioxidant markers such as reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT). Cyclophosphamide elevated the levels of biomarker enzymes like creatine kinase (CK), creatine kinase isoenzyme MB (CK-MB), lactate dehydrogenase (LDH), aspartate transaminase (AST), alanine transaminase (ALT) and alkaline phosphatase (ALP). Further, the cyclophosphamide treated rats showed changes in electrocardiogram (ECG) along with increased levels of cholesterol and triglycerides. Treatment with Saraca indica significantly (p < 0.05) reversed the status of cardiac biomarkers, ECG, oxidative enzymes and lipid profile in cyclophosphamide induced cardiotoxicity. Potential cardioprotective effect of Saraca indica was supported by histopathological examination that reduced severity of cellular damage of the myocardium.

Conclusion:

The biochemical, ECG and histopathology reports support the cardioprotective effect of Saraca indica which could be attributed to antioxidant activity.

Abstract LB-510: Longitudinal imaging of melanoma cancer cell metastasis in a preclinical model by bioluminescence, PET/CT, and MRI

Metastasis of cancer cells from the primary tumor are a leading cause of poor prognosis and death from cancer. The lung is the most common organ for metastatic spread of cancer and leads to 20-50% of cancer-related deaths. Early detection of cancer metastasis to the lung and other organs could be beneficial in disease management. In animal studies, most secondary-site disseminated tumors are evaluated by optical imaging, and gross examination at necropsy and subsequent histopathological analysis. These techniques are limited in that they do not offer the ability to monitor animals during the course of tumor development, and optical microscopy may have inadequate field of view (3-D morphometrics) for thorough tumor evaluation. Noninvasive imaging allows for serial imaging of the same animal, with the ability to repeat measurements in real-time to enhance the observation of disease progression and therapeutic response. Here, we compared the multimodal noninvasive whole-body imaging techniques bioluminescence, 2-deoxy-2-(18F)fluoro-D-glucose (18F-FDG) positron emission tomography (PET)/ computed tomography (CT), and magnetic resonance imaging (MRI) to image lung metastasis development following intravenous injection of melanoma cells (B16-F10 melanoma cell line expressing luciferase gene) in C57BL/6. By bioluminescence imaging, tumor cell localization in the lungs was evident as early as 3 days (1 x 105 photons/sec; total flux) post cancer cell inoculation and steadily increased through the end of week four (1 x 108 photons/sec; total flux). The increase in the lung tumor burden was confirmed by lung histopathology. As it was difficult to de-convolve the effects of photon flux spreading from lungs over other organs, other metastatic sites were not evaluated by bioluminescence. CT and 18F-FDG-PET are used clinically to image lung metastasis and offer excellent resolution of anatomical and metabolic details of cancer cells. We were able to image metastatic nodules in the lung by PET/CT at week four, which showed a strong correlation with histopathology analysis. [18F]FDG-PET/CT also revealed metastasis in the kidney and mesentery and were confirmed by histopathology. T2-weighted MRI at week 4 identified several lung tumors and metastatic cancers in the abdomen. A comparison of [18F]FDG/PET at week 4 to MRI and CT displayed several highly metabolic regions within the tumors. Histopathology confirmed the metastatic spread of the melanoma cells to the lung, mediastinum, kidney, and mesentery. Funded by NCI contract No. HHSN261200800001E.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-510. doi:1538-7445.AM2012-LB-510

Multifunctionality of indocyanine green-loaded biodegradable nanoparticles for enhanced optical imaging and hyperthermia intervention of cancer

The aim of this study was to develop and characterize multifunctional biodegradable and biocompatible poly lactic-co-glycolic acid (PLGA) nanoparticles loaded with indocyanine green (ICG) as an optical-imaging contrast agent for cancer imaging and as a photothermal therapy agent for cancer treatment. PLGA-ICG nanoparticles (PIN) were synthesized with a particle diameter of 246±11 nm, a polydispersity index of 0.10±0.03, and ICG loading efficiency of 48.75±5.48%. PIN were optically characterized with peak excitation and emission at 765 and 810±5 nm, a fluorescence lifetime of 0.30±0.01 ns, and peak absorbance at 780 nm. The cytocompatibility study of PIN showed 85% cell viability till 1-mg/ml concentration of PIN. Successful cellular uptake of ligand conjugated PIN by prostate cancer cells (PC3) was also obtained. Both phantom-based and in vitro cell culture results demonstrated that PIN (1) have the great potential to induce local hyperthermia (i.e., temperature increase of 8 to 10°C) in tissue within 5 mm both in radius and in depth; (2) result in improved optical stability, excellent biocompatibility with healthy cells, and a great targeting capability; (3) have the ability to serve as an image contrast agent for deep-tissue imaging in diffuse optical tomography.

Relative capacities of time-gated versus continuous-wave imaging to localize tissue embedded vessels with increasing depth

Surgeons often cannot see major vessels embedded in adipose tissue and inadvertently injure them. One such example occurs during surgical removal of the gallbladder, where injury of the nearby common bile duct leads to life-threatening complications. Near-infrared imaging of the intraoperative field may help surgeons localize such critical tissue-embedded vessels. We have investigated how continuous-wave (CW) imaging performs relative to time-gated wide-field imaging, presently a rather costly technology, under broad Gaussian beam-illumination conditions. We have studied the simplified case of an isolated cylinder having bile-duct optical properties, embedded at different depths within a 2-cm slab of adipose tissue. Monte Carlo simulations were preformed for both reflectance and transillumination geometries. The relative performance of CW versus time-gated imaging was compared in terms of spatial resolution and contrast-to-background ratio in the resulting simulated images. It was found that time-gated imaging offers superior spatial resolution and vessel-detection sensitivity in most cases, though CW transillumination measurements may also offer satisfactory performance for this tissue geometry at lower cost. Experiments were performed in reflectance geometry to validate simulation results, and potential challenges in the translation of this technology to the clinic are discussed.

Localization of adipose tissue embedded biliary tree vessels by use of near-infrared diffuse photon propagation models: a computational feasibility study

Biliary tree structures are embedded in adipose tissue and, therefore, cannot be visualized directly by the surgeon during cholecystectomy operations. This can lead to inadvertent injuries with serious complications for the patient. Computational studies were performed to assess the feasibility of noninvasively localizing these structures from spectrally resolved near-infrared reflectance measurements. Methodologies were developed for vessel localization, both on the adipose tissue surface and depthwise, by use of semi-infinite and two-layer models of diffuse photon propagation in tissues, respectively. The simulation results, along with some preliminary experimental measurements on tissue-simulating phantoms, prove the feasibility of these methods and show promise for their future clinical application.

Splenic irradiation in chronic myeloid leukemia

Results of splenic irradiation as the initial and only method of treatment are reported in 25 patients with chronic myeloid leukemia. Peripheral remission was induced in all the patients. Induction was achieved after a short period of 11 to 30 days in the majority of the patients, the longest period being 40 days. Several patients were in remission 9 months after treatment. The results are compared with those obtained by chemotherapy. Some advantages of splenic irradiation over chemotherapy are emphasized.

Effect of bleomycin-radiotherapy combination in management of head and neck squamous cell carcinoma

Twenty-five patients with head and neck squamous cell carcinoma were treated with bleomycin-radiotherapy protocol, 15 mg bleomycin I.V. on alternate days followed by radiation within half an hour. The average total dose of bleomycin was 150 mg. Radiotherapy was given daily. Two patients were lost to follow-up very early in the course of the treatment and were removed from the study for statistical purposes. Thirty-six patients with head and neck squamous cell carcinoma who were treated with radiotherapy alone during the same period were used as controls. The patients were followed for two years. The incidence of response rate did not differ significantly between regimens; however the incidence of side effects with bleomycin-radiotherapy, 82.61%, is significantly more than that of radiotherapy alone (52.78%). Median survival time (MST) of those responding to bleomycin-radiotherapy protocol was seven months and 12 days and for radiotherapy responders was six months. Neither the response rate nor the MST improve significantly after pretreatment with bleomycin. On the contrary, the incidence of side effects increased significantly.