Differences In Growth Kinetics Research Articles

Abstract 3923: Targeting immunosuppressive TREM2+tumor associated macrophages in prostate cancer

Abstract With over 250,000 new cases annually, prostate cancer (PCa) is amongst the most diagnosed cancers in the United States. Despite a near-perfect 5-year survival rate in patients with localized disease with androgen deprivation therapy (ADT), about 10-20% of patients on ADT eventually develop castration-resistant prostate cancer (CRPC). Immunotherapies are typically ineffective in treating these treatment-resistant patients due to the abundance of immunosuppressive tumor-associated macrophages (TAMs) and lack of infiltrating lymphocytes. We propose to target these immunosuppressive macrophages through the triggering receptor expressed on myeloid cells 2 (TREM2), which has been identified as a major mediator of suppressive macrophage function but has not been studied in the context of PCa and CRPC. For this study, we analyzed publicly available RNA-seq datasets to query for TREM2 expression amongst patients with a range of prostate cancer disease states and cell types, measured tumor growth kinetics in two subcutaneous models of prostate cancer, and compared tumor immune infiltrates by flow cytometry. Our analysis of the TCGA prostate adenocarcinoma (PRAD) and the Stand Up to Cancer/Prostate Cancer Foundation (SU2C/PCF) datasets implicate TREM2 expression with prostate cancer progression, by Gleason score and progression-free status, and with worse overall survival of patients with metastatic CRPC (mCRPC). Manual curation and analysis of 10 single-cell RNA-seq datasets with a total of 84 patients, encompassing primary PCa, CRPC, and mCRPC indicate that TREM2 is highly and specifically expressed on TAMs in prostate cancer, with macrophages from patient-matched tumor samples expressing higher TREM2 compared to normal adjacent tissue. B6CaP tumors, with a luminal cytokeratin profile, high AR expression, and high Myc expression, show slower tumor growth in Trem2−/− mice compared to tumors in Trem2wt mice. On the other hand, RM1 tumors show no difference in growth kinetics on Trem2−/− mice. A major difference between the B6CaP and RM1 tumor microenvironments is the level of macrophage infiltration, where only 2-5% of immune cells in RM1 tumors are macrophages, compared to the 40-50% in B6CaP tumors. RM1 cells co-implanted with Trem2−/− macrophages show slower tumor growth, compared to tumor cells co-implanted with Trem2wt macrophages, confirming the role of Trem2-expressing macrophages in mediating tumor growth. Consistent with previous reports of suppressive Trem2 signaling, we also observed higher levels of inflammatory cytokine production in ex vivo stimulated Trem2−/− TAMs. By targeting TREM2 in prostate cancer, we find that TAMs are less suppressive, more inflammatory, and permit cytotoxic lymphocyte infiltration to enhance anti-tumor responses by synergizing with chemo and immune checkpoint therapy. Citation Format: Alex J. Lee, Kenneth Adusei, Monali Praharaj, Fan Shen, Xiaoxu Wang, Kaavya Bhatia, Thomas Nirschl, Jelani C. Zarif. Targeting immunosuppressive TREM2+tumor associated macrophages in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3923.

In situ study of growth kinetics of {1 0 0} and {1 1 0} crystal/melt interfaces during unidirectional solidification of silicon

The {100} and {110} solid/liquid interfaces of silicon are considered atomically rough, following the atom-by-atom growth mode during crystallization processes. However, observed differences in growth kinetics are not yet well understood. In this study, the growth behavior of {100} and {110} crystal/melt interfaces in silicon is studied. The growth velocity at different cooling rates is investigated for both growth orientations. Experimental results show that these growth velocities are similar, irrespective of the cooling rate. An analysis of the ratio of the kinetic coefficients of both orientations shows that they are comparable.

Kinetic Optimization of the Batch Crystallization of an Active Pharmaceutical Ingredient in the Presence of a Low-Solubility, Precipitating Impurity

The presence of impurities above regulatory thresholds has been responsible for recent recalls of pharmaceutical drugs. Crystallization is one of the most used separation processes to control impurities in the final drug. A particular issue emerges when impurities are poorly soluble in the crystallization solvent and simultaneously precipitate with the product. This publication reports the development of a population balance model to investigate if the impurity crystallization kinetics can be selectively inhibited in a seeded batch crystallization system containing acetaminophen (ACM), a commonly used small-molecule active pharmaceutical ingredient (API), and curcumin (CUR), a simulated low-solubility/co-precipitating impurity. Raman spectroscopy was used in combination with a partial least squares (PLS) model for in situ monitoring of the crystallization process. The Raman data were integrated to calibrate a population balance model in gPROMS FormulatedProducts, to predict the evolution of the product’s purity throughout the process. Process optimization demonstrated that a high purity close to equilibrium is feasible within the first 2 h of crystallization, with ACM seed purity being the primary factor controlling this phenomenon. The optimal approach for kinetically rejecting impurities requires a low nucleation rate for the impurity, high product seed purities, and an adjustable crystallization time so the process can be stopped before equilibrium without allowing the impurity to nucleate. Overall, an improvement in product purity before equilibrium is attainable if there is enough difference in growth kinetics between the product and impurity, and if one can generate relatively pure seed crystals.

Role of Curing Agents in the Adaptive Response of the Bioprotective Latilactobacillus curvatus CRL 705 from a Physiologic and Proteomic Perspective

During meat processing, lactic acid bacteria (LAB) have to competitively adapt to the hostile environment produced by curing additives (CA). The objective of this study was to investigate the ability of Latilactobacillus curvatus CRL 705, a bioprotective strain of meat origin, to adapt to CA. A physiological and proteomic approach was performed. CRL 705 was grown in a chemically defined medium (CDM) containing specific concentrations of CA (NaCl, nitrite, sucrose, and ascorbic acid). The results showed minor differences in growth kinetics in the presence of CA. Glucose consumption, present in the CDM, and production of lactic acid and bacteriocins were not significantly affected. Proteomic analyses indicated that most of the identified proteins (36 out of 39) mainly related to carbohydrate metabolism (18%), posttranslational modifications (15.6%), energy production and conversion (11.1%), translation (11.1%), and nucleotide metabolism (8.9%) were underexpressed. In response to the studied CA, CRL 705 slowed down its general metabolism, achieving slight changes in physiological and proteomic parameters. The observed performance is another characteristic that extends the well-known competitive profile of CRL 705 as a meat starter and bioprotective culture. This is the first report dealing with the impact of CA on LAB proteomics.

Esophageal Cancer-Derived Organoids to Predict Patients' Treatment Response

The absolute 10-year overall survival of esophageal adenocarcinoma (EAC) has significantly increased from 26% to 36% due to neoadjuvant chemoradiotherapy (nCRT) with consecutive radical resection. However, 20-25% of EAC patients don't respond to nCRT and need alternative treatment, and 20-30% have a complete pathological response and may not need resection. Therefore, there is an urgent need for better models to accurately predict response of EAC to nCRT. Accumulating evidence indicates that patient-derived organoids (PDOs) may predict treatment responses, but the ability of PDOs to predict responses to chemoradiation in EAC patients remains unknown. Hence, we generated patient derived EAC cancer organoids (ec-PDOs) to examine their response to nCRT. The biopsies from treatment-naïve EAC patients after informed consent were used to establish ec-PDOs. Next, we investigated the response of ec-PDOs to the components of standard-of-care neoadjuvant treatment, including irradiation, carboplatin, and paclitaxel. Finally, the potential of ec-PDOs to reflect patients' response to nCRT before esophageal resection was evaluated. Mechanically and enzymatically dispersed patient derived EAC biopsies were cultured as ec-PDOs for up to 10 passages, indicating the self-renewal and expansion potential. These ec-PDOs expressed the EAC marker MUC5AC, indicating the EAC origin. Differences in growth kinetics and response to irradiation, carboplatin, and paclitaxel were observed between patients specific ec-PDOs. However, similar dose-response curves were seen within ec-PDOs from the same patient after different passages. This indicates that ec-PDOs exhibit interpatient response heterogeneity but have good reproducible responses within the same patient. Moreover, after combined treatment with irradiation (IR), carboplatin (Car), and paclitaxel (Pac) to mimic nCRT in EAC patients, the stem cell survival of ec-PDOs from patients with complete response (CR) and partial response (PR) are lower than that from those with progressive disease (PD). The preliminary findings in this study suggest a great potential of ec-PDOs to predict patient-specific responses to neoadjuvant treatment in EAC patients.

Numerical Investigations of Phase Transformations Controlled by Interface Thermodynamic Conditions during Intercritical Annealing of Steels

Austenite formation was numerically investigated using Thermo-Calc/DICTRA in a deformed ferrite/pearlite microstructure to produce dual-phase steels. This work aims to better understand how the interface conditions (local equilibrium with negligible partitioning—LENP—or local equilibrium with partitioning—LEP) control the austenite growth kinetics during the intercritical annealing. Inspired by our experimental observations, two nucleation sites were considered. The austenite formed from pearlite islands showed a regime transition from LENP to LEP when the holding stage started. For the growth of austenite from isolated carbides, three stages were identified during the heating stage: first, slow growth under LEP; then, fast growth under LENP; and finally, after dissolution of the carbide, slow growth again. LENP and LEP interface conditions may coexist thanks to these regime transitions. In the case of competition, LEP conditions hinder austenite growth while it is promoted by LENP interface conditions. Such differences in growth kinetics explain, in part, the morphogenesis of dual-phase microstructures.

The Mucin-Like Domain of the Ebola Glycoprotein Does Not Impact Virulence or Pathogenicity in Ferrets.

Ebola virus (EBOV) is considered among the most dangerous viruses with case fatality rates approaching 90% depending on the outbreak. While several viral proteins (VPs) including VP24, VP35, and the soluble glycoprotein are understood to contribute to virulence, less is known of the contribution of the highly variable mucin-like domain (MLD) of EBOV. Early studies have defined a potential role in immune evasion of the MLD by providing a glycan shield to critical glycoprotein residues tied to viral entry. Nonetheless, little is known as to what direct role the MLD plays in acute EBOV disease (EVD). We generated an infectious EBOV clone that lacks the MLD and assessed its virulence in ferrets compared with wild-type (WT) virus. No differences in growth kinetics were observed in vitro, nor were there any differences in time to death, viremia, or clinical picture in ferrets infected with recombinant EBOV (rEBOV)-WT or rEBOV-Δmucin. The EBOV MLD does not play a critical role in acute pathogenesis of EVD in ferrets.

Abstract A061: Utility of patient-derived organoids for precision pharmacotyping, phenotypic screens, and modeling of pancreatic disease

Abstract Pancreatic ductal adenocarcinoma (PDA) is projected to soon become the second leading cause of cancer death. Aberrant glycosylation is a hallmark of PDA, but the impact of glycosylation remains vastly understudied in PDA. Additionally, a lack of disease models that recapitulate glycosylation differences observed in human disease has hampered efforts to leverage glycan changes as therapeutic strategies. To address these needs, human patient-derived organoids (PDOs) were employed to address three major questions. First, the use of PDOs in drug screening experiments to characterize therapeutic sensitivity and resistance (i.e. “pharmacotyping”) is a promising precision medicine approach to inform clinical decisions. However, the extent to which different sources of basement membrane extracts (BMEs) in which PDOs are cultured contribute to organoid chemosensitivity profiles is unknown. Mouse and human PDA organoids representing a range of PDA disease stages (early, late, and metastasis) were subjected to a chemotherapy and targeted therapy pharmacotyping panel in different commercial BMEs. Differences in growth kinetics and drug response were analyzed. RNA-seq was performed to determine the impact of BME source on gene expression programs. Results from this work will provide key insights regarding optimal growth of pancreatic PDOs as well as the impact of exogenous factors on pharmacotyping results. Second, elevated serum levels of the glycan CA19-9 are observed in more than 75% of PDA patients. Recent evidence demonstrated that CA19-9 promotes pancreatitis and accelerates pancreatic tumorigenesis in mice, phenotypes that are reversible with the use of CA19-9-targeting antibodies. However, how CA19-9 synthesis is regulated is unknown. We developed organoid high-throughput screens to identify compounds that impact CA19-9 production. Continuing this screen across a library of hPDOs will lay the foundation for the identification of new therapeutic candidates and the understanding of regulators of glycosylation in PDA. Lastly, the pancreatitis is a major risk factor for the development of PDA, with hereditary pancreatitis patients having a 40-55% cumulative risk of developing PDA. However, reliable organoid models of human pancreatitis are lacking. To address this need, we optimized methods to derive PDOs from chronic pancreatitis specimens of genetic and non-genetic etiology. Human chronic pancreatitis organoids underwent multi-omic characterization and credentialing in order to provide the field with more representative models of pancreatitis in humans and a platform to explore early detection strategies and study pancreatic disease progression. Overall, we demonstrate the broad utility of PDOs to identify early detection biomarkers and targetable vulnerabilities in PDA. These models are a renewable resource for the field, enabling elucidation of the molecular underpinnings of the increased susceptibility of chronic pancreatitis to PDA and other fundamental aspects of PDA biology. Citation Format: Jan Lumibao, Shira Okhovat, Kristina Peck, Dannielle Engle. Utility of patient-derived organoids for precision pharmacotyping, phenotypic screens, and modeling of pancreatic disease [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr A061.

Fibulin-3 Deficiency Protects Against Myocardial Injury Following Ischaemia/ Reperfusion in in vitro Cardiac Spheroids.

Myocardial infarction (MI, or heart attack) is a leading cause of death worldwide. Myocardial ischaemia reperfusion (I/R) injury typical of MI events is also associated with the development of cardiac fibrosis and heart failure in patients. Fibulin-3 is an extracellular matrix component that plays a role in regulating MI response in the heart. In this study, we generated and compared in vitro cardiac spheroids (CSs) from wild type (WT) and fibulin-3 knockout (Fib-3 KO) mice. These were then exposed to pathophysiological changes in oxygen (O2) concentrations to mimic an MI event. We finally measured changes in contractile function, cell death, and mRNA expression levels of cardiovascular disease genes between WT and Fib-3 KO CSs. Our results demonstrated that there are significant differences in growth kinetics and endothelial network formation between WT and Fib-3 KO CSs, however, they respond similarly to changes in O2 concentrations. Fib-3 deficiency resulted in an increase in viability of cells and improvement in contraction frequency and fractional shortening compared to WT I/R CSs. Gene expression analyses demonstrated that Fib-3 deficiency inhibits I/R injury and cardiac fibrosis and promotes angiogenesis in CSs. Altogether, our findings suggest that Fib-3 deficiency makes CSs resistant to I/R injury and associated cardiac fibrosis and helps to improve the vascular network in CSs.

139D in NS1 Contributes to the Virulence of H5N6 Influenza Virus in Mice.

H5N6, the highly pathogenic avian influenza A virus (IAV) of clade 2.3.4.4, causes global outbreaks in poultry. H5N6 has become the dominant IAV subtype in waterfowls and causes human infections with high mortality rates. Here, we isolated two strains of H5N6, XGD and JX, from chickens and ducks, respectively. Growth kinetics were evaluated in duck embryo fibroblasts, chicken embryo fibroblasts, Madin-Darby canine kidney cells, and A549 lung carcinoma cells. Receptor binding specificity was analyzed via sialic acid–binding activity assay. The virulence of each strain was tested in BALB/c mice, and recombinant viruses were constructed via reverse genetics to further analyze the pathogenicity. The two strains showed no significant differences in growth kinetics in vitro; however, JX was more virulent in mice than XGD. We also identified 13 mutations in six viral proteins of the two strains through genetic analysis. Our study showed that the NS1 protein played a crucial role in enhancing the virulence of JX. Specifically, the amino acid 139D in NS1 contributed to the high pathogenicity. Therefore, 139D in NS1 might provide insight into the underlying mechanism of IAV adaptation in mammals.

Recombinant Duck Enteritis Virus-Vectored Bivalent Vaccine Effectively Protects Against Duck Hepatitis A Virus Infection in Ducks.

Duck enteritis virus (DEV) and duck hepatitis A virus (DHAV) are prevalent duck pathogens, causing significant economic losses in the duck industry annually. Using a fosmid-based rescue system, we generated two DEV recombinants, rDEV-UL26/27-P13C and rDEV-US7/8-P13C, in which the P1 and 3C genes from DHAV type 3 (DHAV-3) were inserted into the DEV genome between genes UL26 and UL27 or genes US7 and US8. We inserted a self-cleaving 2A-element between P1 and 3C, allowing the production of both proteins from a single open reading frame. P1 and 3C were simultaneously expressed in infected chicken embryo fibroblasts, with no difference in growth kinetics between cells infected with the recombinant viruses and those infected with the parent DEV. Both recombinant viruses induced neutralizing antibodies against DHAV-3 and DEV in ducks. A single dose of the recombinant viruses induced solid protection against lethal DEV challenge and completely prevented DHAV-3 infection as early as 7 days post-vaccination. These recombinant P1- and 3C-expressing DEVs provide potential bivalent vaccines against DEV and DHAV-3 infection in ducks.

Dual-coupling-guided epitaxial growth of wafer-scale single-crystal WS2 monolayer on vicinal a-plane sapphire.

The growth of wafer-scale single-crystal two-dimensional transition metal dichalcogenides (TMDs) on insulating substrates is critically important for a variety of high-end applications1-4. Although the epitaxial growth of wafer-scale graphene and hexagonal boron nitride on metal surfaces has been reported5-8, these techniques are not applicable for growing TMDs on insulating substrates because of substantial differences in growth kinetics. Thus, despite great efforts9-20, the direct growth of wafer-scale single-crystal TMDs on insulating substrates is yet to be realized. Here we report the successful epitaxial growth of two-inch single-crystal WS2 monolayer films on vicinal a-plane sapphire surfaces. In-depth characterizations and theoretical calculations reveal that the epitaxy is driven by a dual-coupling-guided mechanism, where the sapphire plane-WS2 interaction leads to two preferred antiparallel orientations of the WS2 crystal, and sapphire step edge-WS2 interaction breaks the symmetry of the antiparallel orientations. These two interactions result in the unidirectional alignment of nearly all the WS2 islands. The unidirectional alignment and seamless stitching of WS2 islands are illustrated via multiscale characterization techniques; the high quality of WS2 monolayers is further evidenced by a photoluminescent circular helicity of ~55%, comparable to that of exfoliated WS2 flakes. Our findings offer the opportunity to boost the production of wafer-scale single crystals of a broad range of two-dimensional materials on insulators, paving the way to applications in integrated devices.

An automated multiplexed turbidometric and data collection system for measuring growth kinetics of anaerobes dependent on gaseous substrates

Standard methods of monitoring the growth kinetics of anaerobic microorganisms are generally impractical when there is a protracted or indeterminate period of active growth, and when high numbers of samples or replications are required. As part of our studies of the adaptive evolution of a simple anaerobic syntrophic mutualism, requiring the characterization of many isolates and alternative syntrophic pairings, we developed a multiplexed growth monitoring system using a combination of commercially available electronics and custom designed circuitry and materials. This system automatically monitors up to 64 sealed, and as needed pressurized, culture tubes and reports the growth data in real-time through integration with a customized relational database. The utility of this system was demonstrated by resolving minor differences in growth kinetics associated with the adaptive evolution of a simple microbial community comprised of a sulfate reducing bacterium, Desulfovibrio vulgaris, grown in syntrophic association with Methanococcus maripaludis, a hydrogenotrophic methanogen.

A global non-invasive methodology for the phenotyping of potato under water deficit conditions using imaging, physiological and molecular tools

BackgroundDrought is a major consequence of global heating that has negative impacts on agriculture. Potato is a drought-sensitive crop; tuber growth and dry matter content may both be impacted. Moreover, water deficit can induce physiological disorders such as glassy tubers and internal rust spots. The response of potato plants to drought is complex and can be affected by cultivar type, climatic and soil conditions, and the point at which water stress occurs during growth. The characterization of adaptive responses in plants presents a major phenotyping challenge. There is therefore a demand for the development of non-invasive analytical techniques to improve phenotyping.ResultsThis project aimed to take advantage of innovative approaches in MRI, phenotyping and molecular biology to evaluate the effects of water stress on potato plants during growth. Plants were cultivated in pots under different water conditions. A control group of plants were cultivated under optimal water uptake conditions. Other groups were cultivated under mild and severe water deficiency conditions (40 and 20% of field capacity, respectively) applied at different tuber growth phases (initiation, filling). Water stress was evaluated by monitoring soil water potential. Two fully-equipped imaging cabinets were set up to characterize plant morphology using high definition color cameras (top and side views) and to measure plant stress using RGB cameras. The response of potato plants to water stress depended on the intensity and duration of the stress. Three-dimensional morphological images of the underground organs of potato plants in pots were recorded using a 1.5 T MRI scanner. A significant difference in growth kinetics was observed at the early growth stages between the control and stressed plants. Quantitative PCR analysis was carried out at molecular level on the expression patterns of selected drought-responsive genes. Variations in stress levels were seen to modulate ABA and drought-responsive ABA-dependent and ABA-independent genes.ConclusionsThis methodology, when applied to the phenotyping of potato under water deficit conditions, provides a quantitative analysis of leaves and tubers properties at microstructural and molecular levels. The approaches thus developed could therefore be effective in the multi-scale characterization of plant response to water stress, from organ development to gene expression.

Abstract 3013: Orthotopic patient-derived xenografts (O-PDX) are effective precision oncology models that can predict therapeutic response, recurrence, and acquired drug resistance

Abstract Patient-derived xenografts provide a functional test system in a living organism, making them the leading assay for precision oncology and drug development. In vivo pharmacology studies are widely performed using subcutaneous implantation; however, due to significant changes in the tumor microenvironment, this methodology falls short of modeling the full complexities of human cancer. We use quantitative magnetic resonance imaging (MRI) to report differences in growth kinetics and pharmacological response between orthotopic and subcutaneous implantation of patient-derived xenografts. We demonstrate that O-PDX models can predict effective treatment strategies for individual patients and forecast tumor recurrence after therapy. Furthermore, we use this approach to develop in vivo models of acquired drug resistance to strategize future treatment options and aid in drug development. Citation Format: Jonathan Nakashima, Jantzen Sperry, Bianca Carapia, Deborah Yan, Angelina Chin, Aliakbar Shahsafaei, Joan Chen, Yuan-Hung Chien, Christophe Pedros, Noah Federman, Arun Singh, Fritz C. Eilber, Brian Datnow. Orthotopic patient-derived xenografts (O-PDX) are effective precision oncology models that can predict therapeutic response, recurrence, and acquired drug resistance [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 3013.

Comparative characterization of the reassortant Orthobunyavirus Ngari with putative parental viruses, Bunyamwera and Batai: in vitro characterization and ex vivo stability.

Bunyamwera (BUNV), Batai (BATV) and Ngari (NRIV) are mosquito-borne viruses that are members of the genus Orthobunyavirus in the order Bunyavirales. These three viruses are enveloped with single-stranded, negative-sense RNA genomes consiting of three segments, denoted as Small (S), Medium (M) and Large (L). Ngari is thought to be the natural reassortant progeny of Bunyamwera and Batai viruses. The relationship between these ‘parental’ viruses and the ‘progeny’ poses an interesting question, especially given that there is overlap in their respective transmission ecologies, but differences in their infection host ranges and pathogenesis. We compared the in vivo kinetics of these three viruses in a common laboratory system and found no significant difference in growth kinetics. There was, however, a tendency of BATV to have smaller plaques than either BUNV or NRIV. Furthermore, we determined that all three viruses are stable in extracellular conditions and retain infectivity for a week in non-cellular media, which has public health and biosafety implications. The study of this understudied group of viruses addresses a need for basic characterization of viruses that have not yet reached epidemic transmission intensity, but that have the potential due to their infectivity to both human and animal hosts. These results lay the groundwork for future studies of these neglected viruses of potential public and One Health importance.

Characterization and Growth Kinetics of a Multispecies Periodontal Biofilm Developed in a Stirred Bioreactor

This study aimed to validate an in vitro periodontal biofilm model with complex subgingival microbial communities grown in a stirred bioreactor. Experimental biofilms were characterized and examined for their growth kinetics over time. After incubation under anaerobic conditions for 3 days, biofilm cultures formed on the substrate were collected and analyzed. The specific growth rate in the exponential phase was estimated to be 0.3915 h−1, with no significant differences in growth kinetics and CFU counts between the replicates (P > 0.05). The biofilm architecture was consistent in each time-point, with bacterial cells presenting different morphology and completely colonizing the cementum surface. To conclude, the three-day subgingival biofilm model developed in our study successfully mimicked the growth of complex microbial communities.

Different growth kinetics in blood components and genetic analysis of Lactococcus garvieae isolated from platelet concentrates.

In 2014, we experienced the first isolation of Lactococcus garvieae from a platelet concentrate (PC). Thereafter, L. garvieae contamination of PCs occurred in two more cases in Japan. It is rare that bacterial contamination with uncommon strains like this species occurs frequently within a short period. Therefore, we performed a detailed analysis of the characteristics of these strains. Three bacterial strains were identified by biochemical testing and molecular analysis. Genomic diversity was characterized by multilocus sequence typing (MLST). To observe growth kinetics in blood components, PCs were inoculated with the three different strains. All three strains were identified as L. garvieae by molecular analysis. Each strain belonged to a different phylogenetic group according to MLST analysis. In the spiking trial, the three strains demonstrated differences in their final concentrations and changes in appearance of PCs. In this study, all three L. garvieae strains were correctly identified by molecular analysis. Since the three strains were collected in different regions of Japan and belonged to different phylogenetic groups according to MLST analysis, it is suggested that L. garvieae have a wide distribution with diversity in Japan. In PCs, the three L. garvieae strains showed clear differences in growth kinetics and changes in appearance of PCs. These differences may have been the primary determinant of whether PC contamination was detected before transfusion. Moreover, L. garvieae represents an emerging foodborne bacterium that can cause transfusion-transmitted bacteremia. Understanding our cases may help prevent bacterial contamination of blood products.

Growth characteristics and therapeutic decision markers in von Hippel-Lindau disease patients with renal cell carcinoma

BackgroundVon Hippel-Lindau (VHL) disease is a multi-systemic hereditary disease associated with several benign and malignant tumor entities, including clear cell renal cell carcinoma (ccRCC). Since ccRCCs grow slowly, nephron sparing surgery is typically performed at a tumor diameter of 3–4 cm before the tumor metastasizes. However, in the case of recurrent disease, repeated surgical intervention can impair renal function. Therefore, it is crucial to optimize the timing for surgical interventions through a better understanding of the growth kinetics of ccRCCs in VHL. We investigated tumor growth kinetics and modern volumetric assessment to guide future therapeutic decisions.ResultsThe prevalence of ccRCC was 28% in a cohort of 510 VHL patients. Of 144 patients with ccRCC, 41 were followed with serial imaging which identified 102 renal tumors, which exhibited heterogeneous growth kinetics. ccRCCs grew at an average absolute growth rate of 0.287 cm/year, an average relative growth rate [(lnV1-lnV0)/(t1-t0)] of 0.42% and an average volume doubling time of 27.15 months. Women had a faster relative growth rate than men. Age and specific mutations did not influence tumor growth. Because of the tumor heterogeneity, we developed an additional cut-off volume of 40 cm3 for surgical intervention.ConclusionsTumor heterogeneity and differences in growth kinetics is suggestive of a state of transient tumor dormancy in ccRCCs of VHL patients. The relative growth rate has not been previously described in other studies. Volumetric assessment as an additional parameter for surgical intervention could be a useful clinical tool and needs further investigation.

Preparation of Few-Layer Graphene/Carbon Nanotube Hybrids Using Oxide Spinel Catalysts

Functional 3D materials can be developed from graphene-based hybrids by introducing other nanomaterials, with multi-walled carbon nanotubes (CNTs) being the most studied additive. For large-scale applications, few-layer graphene (FLG)-CNT hybrids are produced by catalytic chemical vapor deposition (c-CVD) starting from a mixture of catalysts (one for FLG and one for CNTs) in the required proportions. Due to the difference in growth kinetics between CNTs and FLG, the composition of such hybrids is not well controlled. In this study, we report the single-step preparation of FLG-CNT hybrid materials by a fixed-bed c-CVD process using a single catalyst with the formula AlxCo1−xFe2O4 (x = 0.025–0.10). Different catalysts (with varying x) were prepared by the citrate–nitrate gel combustion method. Then, c-CVD synthesis was carried out at 650 °C in a horizontal fixed-bed reactor using ethylene as the carbon source. Only FLG was obtained when using CoFe2O4. However, the introduction of small amounts of Al (x < 0.05) induced the simultaneous production of CNTs, leading to the formation of uniform FLG-CNT hybrids. For catalysts with higher Al content (e.g., AlCoFeO4), CNTs were selectively produced. Thus, we observed the existence of a narrow Al-doping window, where CNTs and FLG can be obtained simultaneously. Our results can pave the way to developing high-yield single catalyst-based CVD synthesis of FLG-CNT hybrid materials.