In vivo magnetic resonance imaging of pancreatic tumors using iron oxide nanoworms targeted with PTR86 peptide.

To cut the high mortality rate of malignant disease such as pancreatic cancer, development of newly diagnostic probes for early stage detection of tumor lesions is required. Multimodal imaging nanoprobes allowing targeted and real time functional/anatomical imaging of tumors meet the demands. For this purpose, a MRI/optical dual-modality probe based on biodegradable magnetic iron oxide nanoworms has been developed. The cross-linked surface of nanoworms were anchored to fluorescent dyes and to FITC.PTR86; a novel synthetic peptide with high affinity towards somatostatin receptors. Combination of various in vitro techniques including Prussian blue staining, fluorescent microscopy and fluorescence activated cell sorting (FACS) have been performed to explore the interaction of developed nanoprobe with pancreatic tumor cell lines. Together with in vivo studies in a xenograft mouse model of human pancreatic adenocarcinoma and ex vivo investigations, the results show the efficient imaging and targeting of pancreatic tumors by our newly developed nanosystem using both MRI and optical imaging modalities.

Functional Single-Chain Polymer Nanoparticles: Targeting and Imaging Pancreatic Tumors in Vivo.

The development of tools for the early diagnosis of pancreatic adenocarcinoma is an urgent need in order to increase treatment success rate and reduce patient mortality. Here, we present a modular nanosystem platform integrating soft nanoparticles with a targeting peptide and an active imaging agent for diagnostics. Biocompatible single-chain polymer nanoparticles (SCPNs) based on poly(methacrylic acid) were prepared and functionalized with the somatostatin analogue PTR86 as the targeting moiety, since somatostatin receptors are overexpressed in pancreatic cancer. The gamma emitter 67Ga was incorporated by chelation and allowed in vivo investigation of the pharmacokinetic properties of the nanoparticles using single photon emission computerized tomography (SPECT). The resulting engineered nanosystem was tested in a xenograph mouse model of human pancreatic adenocarcinoma. Imaging results demonstrate that accumulation of targeted SCPNs in the tumor is higher than that observed for nontargeted nanoparticles due to improved retention in this tissue.

Adipocytes Viability After Suction-Assisted Lipoplasty: Does the Technique Matter?

BACKGROUND: Suction-assisted lipoplasty (SAL; liposuction) is an established aesthetic procedure in plastic surgery. The main parameters differentiating one method of lipoplasty from another are safety, consistency of results, and other more technical parameters. Due to the recent popularity of lipotransfer, the quality of extracted fat has become a relevant parameter. We compare the viability of extracted adipocytes after dry SAL, hyper-tumescent PAL (power-assisted lipoplasty), and water-assisted lipoplasty (WAL). METHODS: We used fluorescent microscopy to differentiate viable from necrotic/apoptotic cells after liposuction using each of the mentioned methods. RESULTS: The ratio of living cells between the three methods was significantly different with dry liposuction yielding inferior ratios (p = 0.011). When omitting extreme results, we found that the body-jet technique (WAL) yielded higher ratios of living cells than the hyper-tumescent technique (p < 0.001). The total number of cells was highest in the hyper-tumescent method (p = 0.013). CONCLUSIONS: Our results indicate that the hyper-tumescent technique yields the highest number of cells, whereas the body-jet technique yields the highest living cells ratio. The dry technique is clearly inferior to both. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Q-Switched Nd:YAG Laser Removal of Facial Amateur Tattoos in Patients With Fitzpatrick Type VI: Case Series.

INTRODUCTION: Q-switched neodymium:YAG (Nd:YAG) lasers are reported to be gold standard for laser tattoo removal. In particular, the Q-switched Nd:YAG laser at 1064 nm is widely recognized for the removal of blue/black amateur tattoos. However, treatment modalities in Fitzpatrick Type VI skin carry a greater risk of complications including alterations in pigmentation compared to fairer skin (Fitzpatrick Type I-IV skin). Therefore, the aim of this case series was to describe with the use of the Q-Switched Nd:YAG laser, the removal of carbon-based amateur tattoos on patients with Fitzpatrick Type VI skin as an effective and safe method. METHODS: Twenty- five patients with Fitzpatrick type VI skin, from Ethiopian origins, with facial tribal tattoos, were treated with the Q- Switched Nd:YAG laser at 1064 nm. Digital images were taken upon every treatment and the clearance rates of the tattoo was evalu- ated by imaging software. RESULTS: We observed an average tattoo clearance rate of 95% among the 45 facial tattoos in 25 patients presented in the case series with minimal pigmentary and textual changes evident. DISCUSSION: These positive aesthetic results have a signi cant psychosocial impact on the lives of those with Fitzpatrick Type VI skin, in particular the Ethiopian Jewish population. J Drugs Dermatol. 2016;15(11):1448-1452..

Radiotherapy-induced basal cell carcinomas of the scalp: are they genetically different?

BACKGROUND: The treatment of tinea capitis using radiotherapy was introduced at the beginning of the twentieth century. In Israel, between 1949 and 1960, approximately 17,000 children underwent radiotherapy treatments for tinea capitis (actual numbers are probably higher due to irradiation in countries of origin as a prerequisite for immigration). Skin cancer presents a major problem for patients who underwent irradiation for the treatment of tinea capitis [aggressive biological behavior, multiple basal cell carcinomas (BCCs), up to 40 lesions in a single patient, with no predisposing condition such as Gorlin's or Bazex's syndromes]. There are ample data in the literature concerning the molecular changes in ultraviolet (UV) radiation-induced BCCs. However, similar data regarding ionizing radiation-induced BCCs are scarce. One work found higher rates of p53 and PTCH (both are tumor suppressor genes whose alterations are associated with BCC formation and frequency, but not biological behavior) abnormalities in post ionizing radiation BCCs. The absence of documented differences in gene expression that would account for a different biological behavior of radiotherapy-related BCCs, coupled with the aggressive and recurrent nature of these lesions, has propelled us to examine these differences by comparing gene expression in BCCs of the scalps of patients who were previously irradiated for tinea capitis in their childhood and of the scalps of patients who were not. METHODS: Tissue samples of excised scalp BCCs from seven previously irradiated patients (five male, two female) and seven not previously irradiated patients (six male, one female) were frozen upon excision and genetically analyzed using DNA microarray chips. RESULTS: No correlation was found between previous ionizing irradiation and gene expression. CONCLUSIONS: The negative results of this study, coupled with the observation of aggressive biological behavior of BCCs in previously irradiated patients merit further attention. Other explanations for the aggressive biological behavior of radiotherapy-induced BCCs come to mind. One such explanation could be that the difference between the groups lies not in the tumor itself, but in the host, who is more susceptible to the local destruction caused by the tumor due to changes in the surrounding tissue (e.g., impaired blood supply due to radiation, structural damage in seemingly healthy skin). This hypothesis will be the focus of further research. LEVEL OF EVIDENCE II: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Examining national burn care policies--is the Israeli burn care alignment based on national data?

The treatment of burn victims constitutes a considerable challenge both to the clinician in regard to mundane treatment and to health systems in regard to structural organization. The state of Israel is in dire need of competent burn care capabilities for political, geographical, and demographic reasons. Israel currently has five designated burn units but no burn center. A review of the recent literature suggests that larger burn centers can convey lower mortality rates and better functional outcomes for severe burn patients in comparison to smaller burn units. The objective of this study is to assess Israel's burn care alignment needs and capabilities based on Israel's burn patient and burn unit data. In addition, the authors aim to compare the burn care alignment capabilities with those of the country's European and American counterparts. Data of all the burn patients hospitalized in Israel's level 1 trauma centers' burn units between the years 1998 and 2005 according to the Israeli Trauma Registry were analyzed. Simultaneously, data regarding the setup and arrangement of each burn unit were obtained from each burn unit director via phone. Between the years 1998 and 2005, 974 adult patients with burns of the second degree or higher spanning 20% TBSA and more were hospitalized in the five hospitals that operate a functional specialized burn unit. The average hospitalization period was 32.4 days while the mortality rate was 21.1%. Currently, Israel's five burn units report possessing 27 burn beds and 14 burn intensive care unit beds. Due to the continuous risk for terror attacks and military campaigns and due to Israel's inability to refer excess burn patients to neighboring countries, Israel desperately needs efficient burn care capabilities. Israel currently trails both the United States and Europe in regard to burn beds and burn centers per population. The annual quantity and severity of burn patients in Israel largely exceeds the amount needed to justify an establishment of a burn center by the current American Burn Association guidelines, while the literature provides vast amount of evidence proving burn centers' efficacy in improving outcome, shortening hospitalization periods, and reducing costs. Taking all these elements into consideration, it might be prudent to establish a national burn center in Israel to promote burn care standards and disaster planning up to international standards.

Ectopic PDX-1 expression directly reprograms human keratinocytes along pancreatic insulin-producing cells fate.

BACKGROUND: Cellular differentiation and lineage commitment have previously been considered irreversible processes. However, recent studies have indicated that differentiated adult cells can be reprogrammed to pluripotency and, in some cases, directly into alternate committed lineages. However, although pluripotent cells can be induced in numerous somatic cell sources, it was thought that inducing alternate committed lineages is primarily only possible in cells of developmentally related tissues. Here, we challenge this view and analyze whether direct adult cell reprogramming to alternate committed lineages can cross the boundaries of distinct developmental germ layers. METHODOLOGY/PRINCIPAL FINDINGS: We ectopically expressed non-integrating pancreatic differentiation factors in ectoderm-derived human keratinocytes to determine whether these factors could directly induce endoderm-derived pancreatic lineage and ß-cell-like function. We found that PDX-1 and to a lesser extent other pancreatic transcription factors, could rapidly and specifically activate pancreatic lineage and ß-cell-like functional characteristics in ectoderm-derived human keratinocytes. Human keratinocytes transdifferentiated along the ß cell lineage produced processed and secreted insulin in response to elevated glucose concentrations. Using irreversible lineage tracing for KRT-5 promoter activity, we present supporting evidence that insulin-positive cells induced by ectopic PDX-1 expression are generated in ectoderm derived keratinocytes. CONCLUSIONS/SIGNIFICANCE: These findings constitute the first demonstration of human ectoderm cells to endoderm derived pancreatic cells transdifferentiation. The study represents a proof of concept which suggests that transcription factors induced reprogramming is wider and more general developmental process than initially considered. These results expanded the arsenal of adult cells that can be used as a cell source for generating functional endocrine pancreatic cells. Directly reprogramming somatic cells into alternate desired tissues has important implications in developing patient-specific, regenerative medicine approaches.

MiRNA expression in psoriatic skin: reciprocal regulation of hsa-miR-99a and IGF-1R.

BACKGROUND: Psoriasis is a complex disease at the cellular, genomic and genetic levels. The role of microRNAs in skin development was shown in a keratinocyte-specific Dicer knockout mouse model. Considering that two main characteristics of psoriasis are keratinocytes hyperproliferation and abnormal skin differentiation, we hypothesized that aberrant microRNA expression contributes to the psoriatic phenotype. Here, we describe the differential expression of miRNAs in psoriatic involved and uninvolved skin as compared to normal skin, revealing an additional aspect of this complex disorder. METHODOLOGY/PRINCIPAL FINDINGS: Expression arrays were used to compare microRNA expression in normal skin versus psoriatic involved and uninvolved skin. Fourteen differentially expressed microRNAs were identified, including hsa-miR-99a, hsa-miR-150, hsa-miR-423 and hsa-miR-197. The expression of these microRNAs was reevaluated by qPCR. IGF-1R, which is involved in skin development and the pathogenesis of psoriasis, is a predicted target of hsa-miR-99a. In an in situ hybridization assay, we found that IGF-1R and miR-99a are reciprocally expressed in the epidermis. Using a reporter assay, we found that IGF-1R is targeted by hsa-miR-99a. Moreover, over expression of miR-99a in primary keratinocytes down-regulates the expression of the endogenous IGF-1R protein. Over expression of miR-99a also inhibits keratinocyte proliferation and increases Keratin 10 expression. These findings suggest that overexpression of hsa-miR-99a in keratinocytes drives them towards differentiation. In primary keratinocytes grown in high Ca(++), miR-99a expression increases over time. Finally, we found that IGF1 increases the expression of miR-99a. CONCLUSIONS/SIGNIFICANCE: We identified several microRNAs that are expressed differentially in normal and psoriatic skin. One of these miRNAs is miR-99a that regulates the expression of IGF-1R. Moreover, miR-99a seems to play a role in the differentiation of keratinocytes. We suggest that miR-99a is one of the regulators of the IGF-1R signaling pathway in keratinocytes. Activation of IGF1 signaling results in elevation of miR-99a which represses the expression of IGF-1R.

A novel fractional micro-plasma radio-frequency technology for the treatment of facial scars and rhytids: a pilot study.

INTRODUCTION: Fractional ablative and non-ablative lasers have gained popularity in the treatment of acne scars and rhytids due to their efficacy and improved tolerability. Plasma and radio frequency (RF) have also emerged as methods for ablative or non-ablative energy delivery. We report preliminary experience with a novel fractional micro-plasma RF device for the treatment of facial acne scars and rhytids. METHODS: Sixteen patients with facial acne scars or rhytids were treated at 4-week intervals. Treatment parameters were titrated to an immediate end point of moderate erythema. The clinical end point for cessation of treatment was the attainment of satisfactory clinical results. Results were monitored photographically up to 3 months after treatment. RESULTS: Acne scars showed marked improvement after two to four treatments. Facial rhytids demonstrated reduced depth after two treatments and marked improvement after four treatments. Treatment was well tolerated by all participants, with transient erythema and short downtime. These results provide initial evidence for the safety and effectiveness of fractional micro-plasma RF as a low-downtime and well-tolerated modality for the treatment of acne scars and facial rhytids.

Silicone nipple shields: an innovative postoperative dressing technique after nipple reconstruction.

BACKGROUND: The newly reconstructed nipple is extremely sensitive to mechanical pressure and shearing forces, which can cause flap necrosis and sloughing of the skin, eventually promoting infection. Current available dressing solutions are cumbersome, inefficient, displeasing, or otherwise not readily obtainable. METHODS: In this study, 10 patients with newly reconstructed nipples were instructed to use breastfeeding nipple shields as the sole means of nipple dressing after the reconstruction procedure. RESULTS: No complications were observed overall. Patients reported full adherence to the postoperative dressing regimen as well as ease of use, availability, low costs, and pleasing aesthetic appearance under garments. DISCUSSION: Silicone breastfeeding nipple shields offer an efficient, affable, cheap, widely available, and aesthetically pleasing form of postoperative dressing for reconstructed nipples. Their use may enhance patient compliance with the dressing regimen and lower the postoperative complication rate.

Systemic dysregulation of CEACAM1 in melanoma patients.

It was previously shown that CEACAM1 on melanoma cells strongly predicts poor outcome. Here, we show a statistically significant increase of serum CEACAM1 in 64 active melanoma patients, as compared to 48 patients with no evidence of disease and 37 healthy donors. Among active patients, higher serum CEACAM1 correlated with LDH values and with decreased survival. Multivariate analysis with neutralization of LDH showed that increased serum CEACAM1 carries a hazard ratio of 2.40. In vitro, soluble CEACAM1 was derived from CEACAM1(+), but neither from CEACAM1(-) melanoma cells nor from CEACAM1(+) lymphocytes, and directly correlated with the number of CEACAM1(+) melanoma cells. Production of soluble CEACAM1 depended on intact de novo protein synthesis and secretion machineries, but not on metalloproteinase function. An unusually high percentage of CEACAM1(+) circulating NK and T lymphocytes was demonstrated in melanoma patients. CEACAM1 inhibited killing activity in functional assays. CEACAM1 expression could not be induced on lymphocytes by serum from patients with high CEACAM1 expression. Further, expression of other NK receptors was impaired, which collectively indicate on a general abnormality. In conclusion, the systemic dysregulation of CEACAM1 in melanoma patients further denotes the role of CEACAM1 in melanoma and may provide a basis for new tumor monitoring and prognostic platforms.

Hard to heal pressure ulcers (stage III-IV): efficacy of injected activated macrophage suspension (AMS) as compared with standard of care (SOC) treatment controlled trial.

The objective of this study was to compare local injections of AMS with SOC treatments for stage III and IV pressure ulcers in elderly patients. It was designed as historically prospective 2-arms non-parallel open controlled trial, and conducted in a department of geriatric medicine and rehabilitation of a university affiliated tertiary hospital. We studied 100 consecutive elderly patients with a total of 216 stage III or IV pressure ulcers, 66 patients were assigned to the AMS group and had their wounds injected, while 38 patients were assigned to the SOC group. Primary outcome was rate of complete wound closure. Time to complete wound closure and 1-year mortality served as secondary outcomes. Statistical analyses were performed at both patient and wound levels. Percentage of completely closed wounds (wound level and patient level) were significantly better (p<0.001/p<0.001, respectively) in all patients in favor of AMS, as well as in the subset of diabetic patients (p<0.001/p<0.001). Similarly, AMS proved significantly better for the subset of those with leg ulcers and with baseline wounds ≤15 cm(2), compared with SOC. There were no statistically significant differences with regard to time to complete closure or 1-year mortality rates in the two groups. It is concluded that there is a significant difference in favor of stage III and IV wound closure rates by AMS, as compared with SOC treatments.

Natural killer lysis receptor (NKLR)/NKLR-ligand matching as a novel approach for enhancing anti-tumor activity of allogeneic NK cells.

BACKGROUND: NK cells are key players in anti tumor immune response, which can be employed in cell-based therapeutic modalities. One of the suggested ways to amplify their anti tumor effect, especially in the field of stem cell transplantation, is by selecting donor/recipient mismatches in specific HLA, to reduce the inhibitory effect of killer Ig-like receptors (KIRs). Here we suggest an alternative approach for augmentation of anti tumor effect of allogeneic NK cells, which is founded on profile matching of donor NK lysis receptors (NKLR) phenotype with tumor lysis-ligands. METHODOLOGY/PRINCIPAL FINDINGS: We show that an NKLR-mediated killing directly correlates with the NKLR expression intensity on NK cells. Considerable donor variability in the expression of CD16, NKp46, NKG2D and NKp30 on circulating NK cells, combined with the stability of phenotype in several independently performed tests over two months, indicates that NKLR-guided selection of donors is feasible. As a proof of concept, we show that melanoma cells are dominantly recognized by three NKLRs: NKG2D, NKp30 and NKp44. Notably, the expression of NKp30 on circulating NK cells among metastatic melanoma patients was significantly decreased, which diminishes their ability to kill melanoma cells. Ex vivo expansion of NK cells results not only in increased amount of cells but also in a consistently superior and predictable expression of NKG2D, NKp30 and NKp44. Moreover, expanded NK cultures with high expression of NKG2D or NKp30 were mostly derived from the corresponding NKG2D(high) or NK30(high) donors. These NK cultures subsequently displayed an improved cytotoxic activity against melanoma in a HLA/KIR-ligand mismatched setup, which was NKLR-dependent, as demonstrated with blocking anti-NKG2D antibodies. CONCLUSIONS/SIGNIFICANCE: NKLR/NKLR-ligand matching reproducibly elicits enhanced NK anti-tumor response. Common NKLR recognition patterns of tumors, as demonstrated here in melanoma, would allow implementation of this approach in solid malignancies and potentially in hematological malignancies, either independently or in adjunction to other modalities.

The safest method of sternal wire extraction post-midsternotomy closure.

BACKGROUND: An incident of fatal pericardial bleeding immediately after the extraction of a sternal wire prompted a search for the most appropriate method for removing sternotomy wire sutures. A model sternum was devised to explore this problem, and several commonly used techniques for wire extraction were evaluated. METHODS: A wooden sternal model was constructed to simulate the dimensional properties of a sternum overlying the mediastinal cavity, and to imitate its tensile characteristics. A Monofil CrNi-316L (Johnson & Johnson, Brunswick, NJ, USA), No. 7 CCS, 9 metric, 4x45-cm wire was passed vertically through drilled holes. The suture was then crossed and pulled, thus joining the two boards and approximating the wire to their deep surface. A latex balloon filled with dye was placed inside under the boards. Wire holders were used to extract the wires, using a linear pulling technique and a coiling around the wire-holder tip technique. Sixty repetitions were performed for each method. RESULTS: In 60 trials of direct linear wire pulling, balloon rupture occurred in 33 (55%), whereas tearing was noted only 15 times out of 60 attempts (25%) when the tense coiling method was used. CONCLUSIONS: Sternotomy wire sutures should be extracted using a controlled technique that ensures safety to vital tissues in close proximity to the sternal bone. The tense coiling procedure offers superior safety when compared to the direct pulling process, demonstrated by a lower incidence of balloon rupture because of the lesser degree of wire flexure. This technique has become the method of choice in our medical center.

Dynamic expression of protective CEACAM1 on melanoma cells during specific immune attack.

An efficient immune response against tumours depends on a well-orchestrated function of integrated components, but is finally exerted by effector tumour-infiltrating lymphocytes (TIL). We have previously reported that homophilic CEACAM1 interactions inhibit the specific killing and interferon-gamma (IFN-gamma) release activities of natural killer cells and TIL. In this study a model for the investigation of melanoma cells surviving long coincubation with antigen-specific TIL is reported. It is demonstrated that the surviving melanoma cells increase their surface CEACAM1 expression, which in turn confers enhanced resistance against fresh TIL. Furthermore, it is shown that this is an active process, driven by specific immune recognition and is at least partially mediated by lymphocyte-derived IFN-gamma. Similar results were observed with antigen-restricted TIL, either autologous or allogeneic, as well as with natural killer cells. The enhanced CEACAM1 expression depends, however, on the presence of IFN-gamma and sharply drops within 48 hr. This may be a mechanism that allows tumour cells to transiently develop a more resistant phenotype upon recognition by specific lymphocytes. Therefore, this work substantiates the melanoma-promoting role of CEACAM1 and marks it as an attractive target for novel immunotherapeutic interventions.

Do burns increase the severity of terror injuries?

The use of explosives and suicide bombings has become more frequent since October 2000. This change in the nature of terror attacks has marked a new era in the Israeli-Palestinian conflict. We previously reported that the incidence of thermal injuries has since risen. However, the rise in the incidence of burns among victims of terror was proportionate to the rise in the incidence of burns among all trauma victims. This paper presents data from the Israeli National Trauma Registry during the years 1997--2003, to compare the severity of injuries and outcome (mortality rates) in terror victims with and without burn injuries. We also compare the severity of injuries and outcome (mortality rates) for patients with terror-attack related burns to non terror-attack related burns during the same period. Data was obtained from the Israeli National Trauma Registry for all patients admitted to 8 to 10 hospitals in Israel between 1997 and 2003. We analyzed and compared demographic and clinical characteristics of 219 terror-related burn patients (terror/burn), 2228 terror patients with no associated burns (Terror/no-burn) and 6546 non terror related burn patients (burn/no-terror). Severity of injuries was measured using the injury severity score, and burn severity by total body surface percentage indices. Admission rates to Intensive Care Units (ICU) and total length of hospitalization were also used to measure severity of injuries. In-hospital mortality rates were used to indicate outcome. Of burn/terror patients, 87.2% suffered other accompanying injuries, compared with 10.4% of burn/no-terror patients. Of burn/terror patients, 49.8% were admitted to ICU compared with only 11.9% of burn/no-terror patients and 23.8% of no-burn/terror patients. Mean length of hospital stay was 18.5 days for the terror/burn group compared with 11.1 days for the burn/no-terror group and 9.5 days for the terror/no-burn group. Burn/terror patients had a significantly higher injury severity score compared with the other groups. In-hospital mortality rate for the burn/no-terror group was 3.4%. The burn/terror group had a mortality rate of 6.4% which was similar to the no-burn/terror group (6.6%). Terror-attack injuries with accompanying burns have a more complex presentation, are of higher severity, and are associated with increased length of hospital stay and a higher ICU admissions rate, compared with terror-attack injuries without burns and non terror-attack related burns. However, mortality rates in terror-attack injuries are not affected by burns.

Diagnostic targeting of colon cancer using a novel fluorescent somatostatin conjugate in a mouse xenograft model.

Colorectal carcinoma is one of the more prevalent, highly malignant human tumors, occurring in about 7% of the population. However, if diagnosed and treated in its early stages, colon cancer is curable. In our study, we used a mouse xenograft model to investigate the capability of a fluorescent conjugate of a novel synthetic somatostatin (SST) analog to improve detection of human colorectal tumors that are characterized by over-expressed SST receptors. Human HT-29 colon carcinomas were induced in nude mice. After administration of the fluorescent SST conjugate, in vivo low- and high-magnification fluorescence microscopy, as well as high-resolution spectrally resolved imaging were performed, and the time-dependent biodistribution was determined quantitatively (using fiber-optic spectroscopy). Administration of the conjugate (at concentrations of 6 mg/kg body weight) enabled targeting small (1-5 mm diameter) tumors with high sensitivity and selectivity. Toxicity studies at dosages up to 1,000 mg/kg body weight did not reveal any drug related abnormalities. In conclusion, the SST conjugate significantly enhanced the detection of HT-29 colon tumors by fluorescence imaging because of a 5- to 8-fold increase in the contrast between malignant and normal tissues.

Quantification of water compartmentation in cell suspensions by diffusion-weighted and T(2)-weighted MRI.

When studying water diffusion in biological systems, any specific signal attenuation curve may be reproduced by a broad range of mathematical functions. Our goals were to quantify the diffusion and T(2) relaxation properties of water in a simple biological system and to study the changes that occur in osmotically stressed cells. Human breast cancer cells were incubated in isotonic or hypotonic osmotic buffers. Diffusion-weighted and T(2)-weighted magnetic resonance images were acquired during sedimentation over 12 h. Diffusion-weighted imaging (DWI) data were analyzed with a biexponential fit, the Kärger model for exchange between two freely diffusing populations and the Price-modified Kärger model accounting for restricted diffusion in spherical geometry. We found that only the Price model provided an accurate quantitative description for water diffusion in both cell systems, independent of acquisition parameters, over the entire density range. Model-derived cell radii, intracellular volume fractions and transmembrane water exchange times were in good agreement with results calculated from light microscopy and with model-free exchange times. T(2) data indicated two populations in fast exchange, with volume fractions clearly different from DWI populations. Hypotonic stress led to higher slow apparent diffusion coefficient, longer T(2) and lower membrane permeability. The tortuosity in a hypotonic cell suspension complied with the Wang model for spherical geometry. Quantitative characterization of biological systems is obtainable by DWI, using appropriate modeling, accounting for water restriction and exchange between compartments.