Ventilation perfusion functional difference images in lung SPECT: A linear and symmetrical scale as an alternative to the ventilation perfusion ratio

PURPOSE

Ventilation Perfusion SPECT is important in the diagnostics of e.g. pulmonary embolism and chronic obstructive pulmonary disease. Classical and reverse mismatched defects can be identified by utilizing the ventilation-perfusion ratio. Unfortunately, this ratio is only linear in the ventilation, the scale is not symmetrical regarding classical and reversed mismatches and small perfusion values give rise to artifacts. The ventilation-perfusion (VQ) difference is developed as an alternative.

METHODS

For both VQ-ratio and VQ-difference a scaling factor for the perfusion is computed, so that voxels with matched ventilation and perfusion (on average) yield zero signal. The relative VQ-difference is calculated by scaling with the summed VQ-signal in each voxel. The scaled VQ-difference is calculated by scaling with the global maximum of this sum.

RESULTS

The relative and scaled differences have a scale from -1 (perfusion only) to + 1 (ventilation only). Image quality of relative VQ-difference and VQ-ratio images is hampered by artifacts from areas with both low perfusion and low ventilation. Ratio and differences have been investigated in ten patients and are shown for three patients (one without defects). Clinical thresholds for the difference images are derived resulting in color maps of relevant (reversed) mismatches with a (reciprocal) ratio larger than two.

CONCLUSIONS

The relative ventilation-perfusion difference is a methodological improvement on the ventilation-perfusion ratio, because it has a symmetrical scale and is bound on a closed domain. A better diagnostic value is expected by utilizing the scaled difference, which represents functional difference instead of relative difference.

The influence of asthma on neuroinflammation and neurodevelopment: From epidemiology to basic models

Asthma is a highly heterogeneous inflammatory disease that can have a significant effect on both the respiratory system and central nervous system. Population based studies and animal models have found asthma to be comorbid with a number of neurological conditions, including depression, anxiety, and neurodevelopmental disorders. In addition, maternal asthma during pregnancy has been associated with neurodevelopmental disorders in the offspring, such as autism spectrum disorders and attention deficit hyperactivity disorder. In this article, we review the most current epidemiological studies of asthma that identify links to neurological conditions, both as it relates to individuals that suffer from asthma and the impacts asthma during pregnancy may have on offspring neurodevelopment. We also discuss the relevant animal models investigating these links, address the gaps in knowledge, and explore the potential future directions in this field.

Bringing function to the forefront of cell therapy: how do we demonstrate potency?

Unlike conventional pharmaceuticals, biologics and Advanced Therapy Medicinal Products (ATMPs) are required to meet a standard of "potency" as part of the final release criteria at completion of manufacture. During early phase clinical trials, most regulatory agencies have been willing to accept very immature potency assays with an expectation that these will be improved, qualified and validated during the clinical development of the drug to Marketing Authorisation Application (MAA) or Biologics License Application (BLA) submission.This model of continuous development of potency assay in parallel with drug development has already led to at least two notable problem cases; namely Iovance and Mesoblast. Both companies completed successful phase III clinical trials but, in both cases, the initial BLA was rejected on the basis that their potency assay for drug product release was inadequate. Fortunately these issues appear to have been overcome in March of this year, with Mesoblast receiving acceptance of their BLA for Remestemcel and Iovance obtaining a rolling BLA approval for Lifileucel.

Fast and Efficient Separation of Eleven Mycosporine-like Amino Acids by UHPLC-DAD and Their Quantification in Diverse Red Algae

Due to their hostile habitats, characterized by a high exposure to UV-A and UV-B radiation, red algae are known to synthesize unique secondary metabolites: mycosporine-like amino acids (MAAs). These small molecules possess an extremely high UV absorption capacity and therefore mainly act as photoprotective agents. In this study, the first ultrahigh-performance liquid chromatography (UHPLC) method with diode-array detection (DAD) was developed for the determination of eleven MAAs in various algal species. All of the analytes could be separated in under 8 min on a Phenomenex Luna Omega C18 1.6 µm column. The mobile phase comprised water with 0.25% formic acid and 20 mM ammonium formate (A) and acetonitrile (B). Elution was carried out in gradient mode. Method validation following ICH guidelines confirmed excellent linearity (R² ≥ 0.9998), selectivity, precision and accuracy (from 97.41 to 103.38%) for all analytes. The assay’s LOD was always 0.01 µg/mL; its LOQ was not higher than 0.04 µg/mL. Practical applicability was assured by analyzing several algae (e.g., Gracilaria chilensis, Pyropia plicata) using the developed method, and results indicated a high variation in MAA profiles as well as content. Whilst some MAAs were only found in specific samples, shinorine, which was always present, occurred in concentrations from 0.05 to 4.14 mg/g of dried biomass. As UHPLC-MS was also feasible, this method showed high flexibility concerning the detection mode, surpassing established procedures for MAA analysis not only concerning separation efficiency and analysis time.

Calculating Half Maximal Inhibitory Concentration (IC50) Values from Glycomics Microarray Data Using GraphPad Prism

Half maximal inhibitory concentration (IC₅₀) is a measurement often used to compare the efficiency of various carbohydrates and their derivatives for inhibition of lectin binding to particular ligands. IC₅₀ values can be calculated using experimental data from various platforms including enzyme-linked immunosorbent assay- (ELISA-)type microtiter plate assays, isothermal titration calorimetry (ITC), or glycan microarrays. In this chapter, we describe methods to fluorescently label a lectin, to carry out a lectin binding inhibition experiment on glycan microarrays, and to calculate the IC₅₀ value of a binding inhibitory molecule using GraphPad Prism software. In the example used to illustrate the method in this chapter, IC₅₀ calculation is demonstrated for inhibition of Maackia amurensis agglutinin (MAA) binding to 3'sialyl-N-acetyllactosamine (3SLN) using free lactose.

Salivary IgA antibody to malondialdehyde-acetaldehyde associates with mild periodontal pocket depth

OBJECTIVE

Oxidized epitopes such as malondialdehyde-acetaldehyde (MAA) play a crucial role in the progression of atherosclerosis through activation of the humoral immune response. The exact mechanism of the association between atherosclerosis and periodontal diseases is not fully understood. The aim of the current study is to evaluate the association of oral humoral immune response to oxidized epitopes with parameters of periodontal disease.

MATERIALS AND METHODS

The Parogene cohort consist of patients who have undergone coronary angiography due to cardiac symptoms. In this study, 423 patients were randomly selected for an extensive oral examination. Salivary Immunoglobulin A to oxidized epitopes and bacterial antigens was determined by chemiluminescence immunoassay.

RESULTS

In a binary logistic regression model adjusted with periodontal disease confounders, periodontal pocket depth (PPD) 4-5 mm associated with salivary IgA antibodies to MAA-LDL (p = 0.034), heat shock protein 60 of Aggregatibacter actinomycetemcomitans (p = 0.045), Porphyromonas gingivalis (p = 0.045), A. actinomycetemcomitans (p = 0.005), P. intermedia (p = 0.020), and total IgA (p = 0.003).

CONCLUSIONS

The current study shows the association of salivary IgA to MAA-LDL with PPD 4-5 mm in a cohort of patients with chronic coronary artery disease. Humoral immune cross-reactivation to oxidized epitopes such MAA-LDL could partly explain the link of periodontitis with systemic diseases.

High-Efficiency Cationic Labeling Algorithm of Macroaggregated Albumin with 68Gallium

Purpose

The generator product radionuclide gallium-68(⁶⁸Ga) is widely used for PET/CT imaging agents and the ⁶⁸Ga-labeled MAA is an attractive alternative to ^99mTc-labeled MAA. Using a commercially available MAA labeling kit for ^99mTc, we presented a reliable synthesis protocol with a highly efficient, organic solvent-free cationic method in GMP conditions in the Scintomics automated synthesis unit.

Methods

The labeling process was performed by incubating for 7 min at 90 ^°C in the borax vial containing the generator product ⁶⁸GaCl₃ MAA-HEPES eluted from the PSH⁺ cartridge with 1.5 mL 5 molar NaCl. Quality control of the final product content was examined, and radiopharmaceutical production was carried out in accordance with GMP guidelines.

Results

⁶⁸Ga eluted from the generator was obtained in more than 99% radiochemical purity and efficiency. In this case, the labeling efficiency was found to be >99%. When the results of SEM-EDX analysis in the final product were examined, it was determined that most of toxic metals were no appreciable in the product content.

Conclusions

The radiochemical and chemical purity of the final product allows direct use without purification steps to remove "free ⁶⁸Ga" or other toxic compounds.

Computational studies on binding, solvent, and pH effects on (S)-propranolol and methacrylic acid complex

Density functional theory methods have been applied to understand binding of (s)-propranolol, a template, to a methacrylic acid molecule acting as a functional monomer using basic 1:1 model. The model has been expanded to study the effect of various pH by adding hydronium and hydroxide ions solvated by water molecules to the template-monomer system, to mimic acidic and basic environments, respectively. This could be considered a model study towards a potential use of molecular imprinting method for the design of a transdermal patch for a topical and direct delivery of (s)-propranolol to hemangiomas. In addition, this study provides detailed binding site analysis of the template and functional monomer verified by the theoretical IR spectra analysis, as well as solvent and pH effects on template-monomer binding energy.

The joint use of 99mTc-MAA-SPECT/CT and cone-beam CT optimizes radioembolization planning

Purpose

To determine which imaging method used during radioembolization (RE) work-up: contrast-enhanced computed tomography (CECT), ^99mTc-MAA-SPECT/CT or cone beam-CT (CBCT), more accurately predicts the final target volume (TgV) as well as the influence that each modality has in the dosimetric calculation.

Methods

TgVs from ^99mTc-MAA-SPECT/CT, CECT and CBCT were consecutively obtained in 24 patients treated with RE and compared with ⁹⁰Y PET/CT TgV. Using the TgVs estimated by each imaging modality and a fictitious activity of 1 GBq, the corresponding absorbed doses by tumor and non-tumoral parenchyma were calculated for each patient. The absorbed doses for each modality were compared with the ones obtained using ⁹⁰Y PET/CT TgV.

Results

^99mTc-MAA-SPECT/CT predicted ⁹⁰Y PET/CT TgV better than CBCT or CECT, even for selective or superselective administrations. Likewise, ^99mTc-MAA-SPECT/CT showed dosimetric values more similar to those obtained with ⁹⁰Y PET/CT. Nevertheless, CBCT provided essential information for RE planning, such as ensuring the total coverage of the tumor and, in cases with more than one feeding artery, splitting the activity according to the volume of tumor perfused by each artery.

Conclusion

The joint use of ^99mTc-MAA-SPECT/CT and CBCT optimizes dosimetric planning for RE procedures, enabling a more accurate personalized approach.

Combined quality and dose-volume histograms for assessing the predictive value of 99mTc-MAA SPECT/CT simulation for personalizing radioembolization treatment in liver metastatic colorectal cancer

Background

The relationship between the mean absorbed dose delivered to the tumour and the outcome in liver metastases from colorectal cancer patients treated with radioembolization has already been presented in several studies. The optimization of the personalized therapeutic activity to be administered is still an open challenge. In this context, how well the ^99mTc-MAA SPECT/CT predicts the absorbed dose delivered by radioembolization is essential. This work aimed to analyse the differences between predictive ^99mTc-MAA-SPECT/CT and post-treatment ⁹⁰Y-microsphere PET/CT dosimetry at different levels. Dose heterogeneity was compared voxel-to-voxel using the quality-volume histograms, subsequently used to demonstrate how it could be used to identify potential clinical parameters that are responsible for quantitative discrepancies between predictive and post-treatment dosimetry.

Results

We analysed 130 lesions delineated in twenty-six patients. Dose-volume histograms were computed from predictive and post-treatment dosimetry for all volumes: individual lesion, whole tumoural liver (TL) and non-tumoural liver (NTL). For all dose-volume histograms, the following indices were extracted: D₉₀, D₇₀, D₅₀, D_mean and D₂₀. The results showed mostly no statistical differences between predictive and post-treatment dosimetries across all volumes and for all indices. Notably, the analysis showed no difference in terms of D_mean, confirming the results from previous studies. Quality factors representing the spread of the quality-volume histogram (QVH) curve around 0 (ideal QF = 0) were determined for lesions, TL and NTL. QVHs were classified into good (QF < 0.18), acceptable (0.18 ≤ QF < 0.3) and poor (QF ≥ 0.3) correspondence. For lesions and TL, dose- and quality-volume histograms are mostly concordant: 69% of lesions had a QF within good/acceptable categories (40% good) and 65% of TL had a QF within good/acceptable categories (23% good). For NTL, the results showed mixed results with 48% QF within the poor concordance category. Finally, it was demonstrated how QVH analysis could be used to define the parameters that predict the significant differences between predictive and post-treatment dose distributions.

Conclusion

It was shown that the use of the QVH is feasible in assessing the predictive value of ^99mTc-MAA SPECT/CT dosimetry and in estimating the absorbed dose delivered to liver metastases from colorectal cancer via ⁹⁰Y-microspheres. QVH analyses could be used in combination with DVH to enhance the predictive value of ^99mTc-MAA SPECT/CT dosimetry and to assist personalized activity prescription.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40658-020-00345-4.

Planning dosimetry for 90 Y radioembolization with glass microspheres: Evaluating the fidelity of 99m Tc-MAA and partition model predictions

PURPOSE

^99m Tc-MAA-SPECT/CT may be used in ⁹⁰ Y-glass microsphere radioembolization treatment planning to assess perfused liver volumes and absorbed dose distributions. The partition model (PM) offers a more detailed planning dosimetry option beyond the single-compartment model more traditionally used in ⁹⁰ Y radioembolization. As ⁹⁰ Y radioembolization treatments shift toward activities and doses that aim to achieve tumor control, accurate and reliable treatment planning dosimetry for both tumors and normal liver (NL) becomes more critical. In this work, we explore the accuracy and precision of ⁹⁰ Y dosimetry predictions from pretherapy ^99m Tc-MAA and PM.

METHODS

Both PM and voxel dosimetry models were used to calculate tumor and NL mean doses using both planning ^99m Tc-MAA and verification ⁹⁰ Y-SPECT/CT in this retrospective analysis of hepatocellular carcinoma cases treated with glass microspheres (NCT01900002, n = 32). Linear regression models were developed at first access, and then later correct, the estimates by (a) ^99m Tc-MAA for ⁹⁰ Y voxel dosimetry and (b) ^99m Tc-MAA PM for voxel dosimetry, separately for both tumors and NL. Bland-Altman analysis was then used to evaluate the accuracy and precision of the regression model predictions with the mean bias and 95% prediction intervals (PI, ±1.96σ). Two categories of cases were stratified (catheter matched vs catheter unmatched) by establishing the level of ^99m Tc-MAA and ⁹⁰ Y catheter position alignment. Only catheter-matched cases were included in the ^99m Tc-MAA vs ⁹⁰ Y voxel dosimetry comparison, while all cases were used to compare dosimetry models (PM vs voxel).

RESULTS

Half (16/32) of cases were deemed catheter matched. ^99m Tc-MAA could reliably predict NL doses in catheter-matched cases after application of the linear model, with mean bias (PI) of -1% (±31%). PM was equivalent to voxel dosimetry for NL doses with mean bias (PI) of 0% (±1%). Even among catheter-matched cases, ^99m Tc-MAA planning for ⁹⁰ Y tumor voxel doses was poor, overestimating dose by an average of nearly 40%. Upon application of the linear model, ^99m Tc-MAA predictions for ⁹⁰ Y tumor voxel dose were only minimally biased (-4%) but possessed very large PI (±104%). PM predictions for tumor voxel dose using the linear model also showed small bias (-6%) but maintained similarly high PI of ±90%. Cases with tumors representing a large majority (>80%) of the total tumor volume demonstrated the best scenarios for ^99m Tc-MAA and PM tumor dose predictions, with mean biases (PI) of -3% (±53%) and -4% (±21%), respectively.

CONCLUSION

The unconditional use of ^99m Tc-MAA to predict ⁹⁰ Y dosimetry across all cases is not recommended due to: (a) demonstrated the risk of unmatched catheter positions between procedures, and (b) large bias and uncertainty in ^99m Tc-MAA predictions in cases with matched catheter locations. However, NL voxel dose predictions with ^99m Tc-MAA are clinically viable and either PM or voxel dosimetry can be used to produce equivalent predictions. Both ^99m Tc-MAA and PM can provide tumor dose predictions with potential clinical utility, but only in catheter-matched cases and with tumors comprising a clear majority (>80%) of the total tumor volume. These findings stratify the predictive fidelity of ^99m Tc-MAA- and PM-based treatment planning for ⁹⁰ Y dosimetry in improving treatment outcomes.

Analysis of differences between 99mTc-MAA SPECT- and 90Y-microsphere PET-based dosimetry for hepatocellular carcinoma selective internal radiation therapy

Background

The aim of this study was to compare predictive and post-treatment dosimetry and analyze the differences, investigating factors related to activity preparation and delivery, imaging modality used, and interventional radiology.

Methods

Twenty-three HCC patients treated by selective internal radiation therapy with ⁹⁰Y glass microspheres were included in this study. Predictive and post-treatment dosimetry were calculated at the voxel level based on ^99mTc-MAA SPECT/CT and ⁹⁰Y-microsphere PET/CT respectively. Dose distribution was analyzed through mean dose, metrics extracted from dose-volume histograms, and Dice similarity coefficients applied on isodoses. Reproducibility of the radiological gesture and its influence on dose deviation was evaluated.

Results

⁹⁰Y delivered activity was lower than expected in 67% (16/24) of the cases mainly due to the residual activity. A mean deviation of − 6 ± 11% was observed between the delivered activity and the ⁹⁰Y PET’s FOV activity. In addition, a substantial difference of − 20 ± 8% was measured on ⁹⁰Y PET images between the activity in the liver and in the whole FOV. After normalization, ^99mTc-MAA SPECT dosimetry was highly correlated and concordant with ⁹⁰Y-microsphere PET dosimetry for all dose metrics evaluated (ρ = 0.87, ρ_c = 0.86, P = 3.10⁻⁸ and ρ = 0.91, ρ_c = 0.90, P = 7.10⁻¹⁰ for tumor and normal liver mean dose respectively for example). Besides, mean tumor dose deviation was lower when the catheter position was identical than when it differed (16 Gy vs. 37 Gy, P = 0.007). Concordance between predictive and post-treatment dosimetry, evaluated with Dice similarity coefficients applied on isodoses, significantly correlated with the distance of the catheter position from artery bifurcation (P = 0.04, 0.0004, and 0.05, for 50 Gy, 100 Gy, and 150 Gy isodoses respectively).

Conclusions

Discrepancies between planned activity and activity measured on ⁹⁰Y PET images were observed and seemed to be mainly related to clinical hazards and equipment issues. Predictive vs. post-treatment comparison of relative dose distributions between tumor and normal liver showed a good correlation and no significant difference highlighting the predictive value of ^99mTc MAA SPECT/CT-based dosimetry. Besides, the reproducibility of catheter tip position appears critical in the agreement between predictive and actual dose distribution.

Quantitative comparison of pre-therapy 99mTc-macroaggregated albumin SPECT/CT and post-therapy PET/MR studies of patients who have received intra-arterial radioembolization therapy with 90Y microspheres

OBJECTIVE

The aim of our study was to compare yttrium -90 (⁹⁰Y) dosimetry obtained from pre-therapy ^99mTc-macroaggregated albumin (MAA) SPECT/CT versus post-therapy PET/MRI imaging among patients with primary or metastatic hepatic tumors.

MATERIALS AND METHODS

Prior to ⁹⁰Y radioembolization (RE), 32 patients underwent a scan using MAA mimicking ⁹⁰Y distribution. After RE with ⁹⁰Y microspheres, the patients were imaged on a PET/MRI system. Reconstructed images were transferred to a common platform and used to calculate ⁹⁰Y dosimetry. The Passing-Bablok regression scatter diagram and the Bland and Altman method were used to analyze the difference between dosimetry values.

RESULTS

For MAA and PET/MRI modalities, the mean liver doses for all 32 subjects were 43.0 ± 20.9 Gy and 46.5 ± 22.7 Gy, respectively, with a mean difference of 3.4 ± 6.2 Gy. The repeatibility coefficient was 12.1 (27.0% of the mean). The Spearman rank correlation coefficient was high (ρ = 0.92). Although, there was a substantial difference in the maximum doses to the liver between the modalities, the mean liver doses were relatively close, with a difference of 24.0% or less.

CONCLUSIONS

The two main contributors to the difference between dosimetry calculations using MAA versus ⁹⁰Y PET/MRI can be attributed to the changes in catheter positioning as well as the liver ROIs used for the calculations. In spite of these differences, our results demonstrate that the dosimetry values obtained from pre-therapy MAA SPECT/CT scans and PET/MRI post-therapy ⁹⁰Y studies were not significantly different.

Treatment of Primary Liver Tumors and Liver Metastases, Part 1: Nuclear Medicine Techniques

⁹⁰Y radioembolization is an increasingly used treatment for both primary and metastatic malignancy in the liver. Understanding the biophysical properties, dosing concerns, and imaging appearance of this treatment is important for interventional radiologists and nuclear medicine physicians to provide important therapy. ⁹⁰Y radioembolization is efficacious and safe, although the possibility of complications does exist. This article provides a comprehensive in-depth discussion about the indications for ⁹⁰Y radioembolization, reviews the role of preprocedural angiography and ^99mTc-macroaggregated albumin scans, illustrates different dosing techniques, compares and contrasts resin and glass microspheres, and describes potential complications.

Effects of metamizole, MAA, and paracetamol on proliferation, apoptosis, and necrosis in the pancreatic cancer cell lines PaTu 8988 t and Panc-1

BACKGROUND

Adenocarcinoma of the pancreas is one of the most aggressive cancer diseases affecting the human body. Recent research has shown the importance of the perioperative phase in disease progression. Particularly during this vulnerable phase, substances such as metamizole and paracetamol are given as general anesthetics and postoperative analgesics. Therefore, the effects of metamizole and paracetamol on tumor progression should be investigated in more detail because the extent to which these substances influence the carcinogenesis of pancreatic carcinoma is still unclear. This study analyzed the influence of metamizole and its active metabolites MAA (4-N-methyl-aminoantipyrine) and paracetamol on the proliferation, apoptosis, and necrosis of the pancreatic cancer cell lines PaTu 8988t and Panc-1 in vitro.

METHODS

Cell proliferation was measured by means of the ELISA BrdU assay and the rate of apoptosis by flow cytometry using the Annexin V assay.

RESULTS

Metamizole and paracetamol significantly inhibited cell proliferation in pancreatic cancer cells. After the addition of metamizole to PaTu 8988t cells, the rate of apoptosis was reduced after 3 h of incubation but significantly increased after 9 h of incubation.

CONCLUSION

The oncogenic potential of pancreatic adenocarcinoma is mainly characterized by its extreme growth rate. Non-opioid analgesics such as metamizole and paracetamol are given as general anesthetics and postoperative analgesics. The combination of metamizole or paracetamol with cytotoxic therapeutic approaches may achieve synergistic effects. Further studies are necessary to identify the underlying mechanisms so that new therapeutic options may be developed for the treatment of this aggressive tumor.

Rapid Synthesis of 68Ga-labeled macroaggregated human serum albumin (MAA) for routine application in perfusion imaging using PET/CT

^99mTc-labeled MAA is commonly used for single photon emission computed tomography SPECT. In contrast, positron emission tomography/CT (PET/CT) delivers images with significantly higher resolution. The generator produced radionuclide ⁶⁸Ga is widely used for PET/CT imaging agents and ⁶⁸Ga-labeled MAA represents an attractive alternative to ^99mTc-labeled MAA. We report a simple and rapid NaCl based labeling procedure for the labeling of MAA with ⁶⁸Ga using a commercially available MAA labeling kit for ^99mTc. The procedure delivers ⁶⁸Ga-labeled MAA with a high specific activity and a high labeling efficiency (>99%). The synthesis does not require a final step of separation or the use of organic solvents.

Tailoring 99mTc-Macroaggregated Albumin Administration to Optimize Patient Dose Reduction

In the ever-changing field of nuclear medicine, best-practice considerations cannot simply go unchallenged for months and years, with the need to minimize radiation exposure to patients highlighted in "as low as reasonably achievable" principles. The Australian Radiation Protection and Nuclear Safety Agency reports that the dose for (99m)Tc-macroaggregated albumin ((99m)Tc-MAA) administered should be 180-200 MBq. An objective of imaging in pulmonary embolism, or indeed any diagnostic procedure involving radiation, is to minimize radiation exposure without sacrificing image quality and diagnostic accuracy. The amount of radiation involved must be considered together with imaging protocols. Our aim was to reduce the amount of (99m)Tc-MAA administered without compromising the diagnostic quality of the scan.

METHODS

To achieve a ventilation-to-perfusion ratio of 1:4, we ventilated the patient as per standard protocol and then placed intravenous access into the patient. For the perfusion component, 180-200 MBq were prepared in a 2-mL injection. Aliquots of 0.5 mL of (99m)Tc-MAA were administered every 30 s followed by a 5-mL saline flush until the required ventilation-to-perfusion ratio was achieved.

RESULTS

With this protocol, the average administered dose was 105 ± 20.7 MBq (vs. 180 ± 5.3 MBq, P < 0.0001).

CONCLUSION

By individually tailoring the administered dose, diagnostic quality is maintained while achieving a significant dose reduction.

Aminomethylphosphonic acid and methoxyacetic acid induce apoptosis in prostate cancer cells

Aminomethylphosphonic acid (AMPA) and its parent compound herbicide glyphosate are analogs to glycine, which have been reported to inhibit proliferation and promote apoptosis of cancer cells, but not normal cells. Methoxyacetic acid (MAA) is the active metabolite of ester phthalates widely used in industry as gelling, viscosity and stabilizer; its exposure is associated with developmental and reproductive toxicities in both rodents and humans. MAA has been reported to suppress prostate cancer cell growth by inducing growth arrest and apoptosis. However, it is unknown whether AMPA and MAA can inhibit cancer cell growth. In this study, we found that AMPA and MAA inhibited cell growth in prostate cancer cell lines (LNCaP, C4-2B, PC-3 and DU-145) through induction of apoptosis and cell cycle arrest at the G1 phase. Importantly, the AMPA-induced apoptosis was potentiated with the addition of MAA, which was due to downregulation of the anti-apoptotic gene baculoviral inhibitor of apoptosis protein repeat containing 2 (BIRC2), leading to activation of caspases 7 and 3. These results demonstrate that the combination of AMPA and MAA can promote the apoptosis of prostate cancer cells, suggesting that they can be used as potential therapeutic drugs in the treatment of prostate cancer.

Regional annular geometry in patients with mitral regurgitation: implications for annuloplasty ring selection

BACKGROUND

The saddle shape of the normal mitral annulus has been quantitatively described by several groups. There is strong evidence that this shape is important to valve function. A more complete understanding of regional annular geometry in diseased valves may provide a more educated approach to annuloplasty ring selection and design. We hypothesized that mitral annular shape is markedly distorted in patients with diseased valves.

METHODS

Real-time 3-dimensional echocardiography was performed in 20 patients with normal mitral valves, 10 with ischemic mitral regurgitation, and 20 with myxomatous mitral regurgitation (MMR). Thirty-six annular points were defined to generate a 3-dimensional model of the annulus. Regional annular parameters were measured from these renderings. Left ventricular inner diameter was obtained from 2-dimensional echocardiographic images.

RESULTS

Annular geometry was significantly different among the three groups. The annuli were larger in the MMR and in the ischemic mitral regurgitation groups. The annular enlargement was greater and more pervasive in the MMR group. Both diseases were associated with annular flattening, although though the regional distribution of that flattening was different between groups. Left ventricular inner diameter was increased in both groups. However, relative to the Left ventricular inner diameter, the annulus was disproportionately dilated in the MMR group.

CONCLUSIONS

Patients with MMR and ischemic mitral regurgitation have enlarged and flattened annuli. In the case of MMR, annular distortions may be the driving factor leading to valve incompetence. These data suggest that the goal of annuloplasty should be the restoration of normal annular saddle shape and that the use of flexible, partial, and flat rings may be ill advised.

Particle assemblies: toward new tools for regenerative medicine

Regenerative medicine is a demanding field in terms of design and elaboration of materials able to meet the specifications that this application imposes. The regeneration of tissue is a multiscale issue, from the signaling molecule through cell expansion and finally tissue growth requiring a large variety of cues that should be delivered in place and time. Hence, the materials should be able to accommodate cells with respect to their phenotypes, to allow cell division to the right tissue, to maintain the integrity of the surrounding sane tissue, and eventually use their signaling machinery to serve the development of the appropriate neo-tissue. They should also present the ability to deliver growth factors and regulate tissue development, to be degraded into safe products, in order not to impede tissue development, and finally be easily implanted/injected into the patients. In this context, colloid-based materials represent a very promising family of products because one can take advantage of their high specific area, their capability to carry/deliver bio-active molecules, and their capacity of assembling (eventually in vivo) into materials featuring other mechanical, rheological, physicochemical properties. Other benefits of great interest would be their ease of production even via high through-put processes and their potential manufacturing from safe, biodegradable and biocompatible parent raw material. This review describes the state-of-the-art of processes leading to complex materials from the assembly of colloids meeting, at least partially, the above-described specifications for tissue engineering and regenerative medicine.